Venezuela has accused the United States of the "greatest extortion" at an emergency session of the UN Security Council in New York.

Washington's seizure of two Venezuelan oil tankers was "worse than piracy," the Venezuelan ambassador to the UN said.

The emergency meeting of the Security Council was called to discuss the seizure of the tankers, which took place off the coast of Venezuela earlier this month.

The US has also said it was pursuing a third Venezuelan oil tanker.

President Trump has accused Venezuela's President Nicolas Maduro of leading a drugs cartel and said gangs had operated with impunity for too long.

On 16 December, Trump ordered a naval blockade of all sanctioned oil tankers entering and leaving Venezuela.

The US president has said the US will keep or sell the crude oil it has taken, as well as the vessels themselves.

The US has been building up its military presence in the Pacific and Caribbean Seas in recent months, sending 15,000 troops and a range of aircraft carriers and warships to the area.

It is the largest deployment to the region since the US invaded Panama in 1989, and the stated aim is to stop the flow of fentanyl and cocaine to the US.

The US has carried out strikes on what it says are Venezuelan drug-smuggling boats, targeting more than 20 vessels and killing at least 100 people.

Some experts say the strikes could violate laws governing armed conflict.

Venezuela's envoy to the UN said the US was subjecting his country to the "greatest extortion" in its history.

Speaking at the UN Security Council meeting on Tuesday, Samuel Moncada said "we are in the presence of a power that acts outside of international law, demanding that Venezuelans vacate our country and hand it over."

Regarding the US seizure of Venezuelan oil, he added: "We are talking about pillaging, looting and recolonisation of Venezuela.

"The government of the United States does not have jurisdiction in the Caribbean."

Referring to the Venezuelan oil industry, he said: "What does that have to do with drugs?"

In response, the US Ambassador to the UN, Michael Waltz, told the Security Council the US does not recognise Mr Maduro as the legitimate leader of Venezuela.

"Maduro's ability to sell Venezuela's oil enables his fraudulent claims to power and his narco-terrorist activities," Mr Waltz said.

On a visit to a trade fair in Caracas, President Maduro said "the Security Council is giving overwhelming support to Venezuela."

Russia and China accused the US of bullying and aggression.

The US was "illegally destroying" civilian vessels in the Caribbean Sea, the Russian ambassador to the UN, Vassily Nebenzia, told the UN meeting.

He warned that other countries could be next.

The US actions against Venezuelan vessels, he said, were "a template for future acts of force against Latin American states."

Meanwhile, China's envoy to the UN, Sun Lei, called on the US to "immediately halt relevant actions and avoid further escalation of tensions."