An Indian pharmaceutical company is manufacturing unlicensed, highly addictive opioids and exporting them illegally to West Africa where they are driving a major public health crisis in countries including Ghana, Nigeria, and Cote D'Ivoire, a BBC Eye investigation has revealed.

Aveo Pharmaceuticals, based in Mumbai, makes a range of pills that go under different brand names and are packaged to look like legitimate medicines. But all contain the same harmful mix of ingredients: tapentadol, a powerful opioid, and carisoprodol, a muscle relaxant so addictive it's banned in Europe.

This combination of drugs is not licensed for use anywhere in the world and can cause breathing difficulties and seizures. An overdose can kill. Despite the risks, these opioids are popular as street drugs in many West African countries, because they are so cheap and widely available.

The BBC World Service found packets of them, branded with the Aveo logo, for sale on the streets of Ghanaian, Nigerian, and Ivoirian towns and cities.

Having traced the drugs back to Aveo's factory in India, the BBC sent an undercover operative inside the factory, posing as an African businessman looking to supply opioids to Nigeria. Using a hidden camera, the BBC filmed one of Aveo's directors, Vinod Sharma, showing off the same dangerous products the BBC found for sale across West Africa.

In the secretly recorded footage, the operative tells Sharma that his plan is to sell the pills to teenagers in Nigeria "who all love this product". Sharma doesn't flinch. "OK," he replies, before explaining that if users take two or three pills at once, they can "relax" and agrees they can get "high". Towards the end of the meeting, Sharma says: "This is very harmful for the health," adding "nowadays, this is business."

It is a business that is damaging the health and destroying the potential of millions of young people across West Africa.

In the city of Tamale, in northern Ghana, so many young people are taking illegal opioids that one of the city's chiefs, Alhassan Maham, has created a voluntary task force of about 100 local citizens whose mission is to raid drug dealers and take these pills off the streets.

"The drugs consume the sanity of those who abuse them," says Maham, "like a fire burns when kerosene is poured on it." One addict in Tamale put it even more simply. The drugs, he said, have "wasted our lives".

The BBC team followed the task force as they jumped on to motorbikes and, following a tip off about a drug deal, launched a raid in one of Tamale's poorest neighbourhoods. On the way they passed a young man slumped in a stupor who, according to locals, had taken these drugs.

When the dealer was caught, he was carrying a plastic bag filled with green pills labelled Tafrodol. The packets were stamped with the distinctive logo of Aveo Pharmaceuticals.

It's not just in Tamale that Aveo's pills are causing misery. The BBC found similar products, made by Aveo, have been seized by police elsewhere in Ghana.

We also found evidence that Aveo's pills are for sale on the streets of Nigeria and Cote D'Ivoire, where teenagers dissolve them in an alcoholic energy drink to increase the high.

Publicly-available export data show that Aveo Pharmaceuticals, along with a sister company called Westfin International, is shipping millions of these tablets to Ghana and other West African countries.

Nigeria, with a population of 225 million people, provides the biggest market for these pills. It has been estimated that about four million Nigerians abuse some form of opioid, according to Nigeria's National Bureau of Statistics.

The Chairman of Nigeria's Drug and Law Enforcement Agency (NDLEA), Brig Gen Mohammed Buba Marwa, told the BBC, opioids are "devastating our youths, our families, it's in every community in Nigeria".

In 2018, following a BBC Africa Eye investigation into the sale of opioids as street drugs, Nigerian authorities tried to get a grip on a widely abused opioid painkiller called tramadol.

The government banned the sale of tramadol without prescription, imposed strict limits on the maximum dose, and cracked down on imports of illegal pills. At the same time, Indian authorities tightened export regulations on tramadol.

Not long after this crackdown, Aveo Pharmaceuticals began to export a new pill based on tapentadol, an even stronger opioid, mixed with the muscle-relaxant carisoprodol.

West African officials are warning that opioid exporters appear to be using these new combination pills as a substitute for tramadol and to evade the crackdown.

In the Aveo factory there were cartons of the combination drugs stacked on top of each other, almost ceiling-high. On his desk, Vinod Sharma laid out packet after packet of the tapentadol-carisoprodol cocktail pills that the company markets under a range of names including Tafrodol, the most popular, as well as TimaKing and Super Royal-225.

He told the BBC's undercover team that "scientists" working in his factory could combine different drugs to "make a new product".

Aveo's new product is even more dangerous than the tramadol it has replaced. According to Dr Lekhansh Shukla, assistant professor at the National Institute of Mental Health and Neuro Sciences in Bengaluru, India, tapentadol "gives the effects of an opioid" including very deep sleep.

"It could be deep enough that people don't breathe, and that leads to drug overdose," he explained. "And along with that, you are giving another agent, carisoprodol, which also gives very deep sleep, relaxation. It sounds like a very dangerous combination."

Carisoprodol has been banned in Europe because it is addictive. It is approved for use in the US but only for short periods of up to three weeks. Withdrawal symptoms include anxiety, insomnia, and hallucinations.

When mixed with tapentadol the withdrawal is even "more severe" compared to regular opioids, said Dr Shukla. "It's a fairly painful experience."

He said he knew of no clinical trials on the efficacy of this combination. Unlike tramadol, which is legal for use in limited doses, the tapentadol-carisoprodol cocktail "does not sound like a rational combination", he said. "This is not something that is licensed to be used in our country."

In India, pharmaceutical companies cannot legally manufacture and export unlicensed drugs unless these drugs meet the standards of the importing country. Aveo ships Tafrodol and similar products to Ghana, where this combination of tapentadol and carisoprodol is, according to Ghana's national Drug Enforcement Agency, unlicensed and illegal. By shipping Tafrodol to Ghana, Aveo is breaking Indian law.

We put these allegations to Vinod Sharma and Aveo Pharmaceuticals. They did not respond.

The Indian drugs regulator, the CDSCO, told us the Indian government recognises its responsibility towards global public health and is committed to ensuring India has a responsible and strong pharmaceutical regulatory system.

It added that exports from India to other countries are closely monitored and that recently tightened regulation is strictly enforced. It also called importing countries to support India's efforts by ensuring they had similarly strong regulatory systems.

The CDSCO stated it has taken up the matter with other countries, including those in West Africa, and is committed to working with them to prevent wrongdoing. The regulator said it will take immediate action against any pharmaceutical firm involved in malpractice.

Aveo is not the only Indian company making and exporting unlicensed opioids. Publicly available export data suggest other pharma companies manufacture similar products, and drugs with different branding are widely available across West Africa.

These manufacturers are damaging the reputation of India's fast-growing pharmaceutical industry, which makes high-quality generic medicines upon which millions of people worldwide depend and manufactures vaccines which have saved millions of lives. The industry's exports are worth at least $28bn (£22bn) a year.

Speaking about his meeting with Sharma, the BBC's undercover operative, whose identity must remain concealed for his safety, says: "Nigerian journalists have been reporting on this opioid crisis for more than 20 years but finally, I was face to face… with one of the men at the root of Africa's opioid crisis, one of the men who actually makes this product and ships it into our countries by the container load. He knew the harm it was doing but he didn't seem to care… describing it simply as business."

Back in Tamale, Ghana, the BBC team followed the local task force on one final raid that turned up even more of Aveo's Tafrodol. That evening they gathered in a local park to burn the drugs they had seized.

"We are burning it in an open glare for everybody to see," said Zickay, one of the leaders, as the packets were doused in petrol and set ablaze, "so it sends a signal to the sellers and the suppliers: if they get you, they'll burn your drugs".

But even as the flames destroyed a few hundred packets of Tafrodol, the "sellers and suppliers" at the top of this chain, thousands of miles away in India, were churning out millions more - and getting rich on the profits of misery.