The couple landed in Abuja on Friday morning, and began their visit with a tour of Lightway Academy, a primary and secondary school in the capital city.

They were greeted by traditional dancers and met some of the primary schoolchildren.

One group of year five pupils told the BBC they were really excited about the visit, saying they hope it will raise their school's profile.

During their tour the couple visited a kindergarten class where children aged up to five danced and sang - at one point, the visitors got to their feet and joined the class in singing Jump Up, Turn Around.

The couple mentioned their own family: Archie, who turned five earlier this month, and two-year-old Lilibet.

Meghan said that dancing was Lilibet's favourite class, adding: "Maybe it’s all the jumping around."

During a visit to a STEM class, when pupils showed the robot cars they had created, the duchess said that Archie also liked construction.

When told by the class that they would be showing the robot cars in class one day, Meghan said: "We will have to come back for the exhibition."

The couple then spoke to students to deliver remarks launching a two-day mental health summit.

Meghan began by telling the audience: “We have got to acknowledge those amazing dance moves” saying Harry was excited and nearly jumped up to join.

Harry asked the children to put their hands up if the words "mental health" scare them or if they know what they mean, before going on to talk about the stigma surrounding mental health worldwide.

The duke told the children the message he wanted them to remember was that mental health affects everyone in the world.

"The more you talk about it, the more you can kick it in the long grass”.

He made the children promise, after Friday, not to be scared of talking about their mental health, and ended his speech with: “It’s okay, not to be okay.”

He then handed the microphone to Meghan who joked: “Do you see why I married him he’s so smart."

She then went on to encourage the children to share their stories, saying that Lilibet once said to her: “Mama, I see me in you.”

Even though she meant literally, Meghan said she hung onto the words, saying she sees herself in her daughter but also all the students there.

“I believe in you”, she told them.

The couple were also joined on stage by Brian, one of three Lightway Academy students who spoke on stage about mental health.

"Both boys and girls have feelings and emotions they bottle up because they can’t really express it… it can lead to suicide," he said.

He went on to add that he hoped the summit would enlighten him and teach him more about mental health.

Lightway Academy's School Director, Joyce Agbese, told the BBC mental health is a topic not often talked about in Nigeria.

She praised Prince Harry's message to the students, which was to "speak up and speak out, don’t bottle things up".

"He nailed it, basically yes. We want to encourage them to speak out, speak up, express their emotions in the right way," said Ms Agbese.

“When somebody this popular or this famous speaks about mental health it makes people realise that it’s normal and so they don’t have to be afraid to talk about it."

The prince wrote: "Keep inspiring others, smashing stigma, and making a difference."

She told the BBC: "I think it’s very important because I personally go through some mental health issues; I have anxiety, I suffer from depression from now and then and it’s really nice that people still don’t really think it’s a taboo anymore to speak on these things, and it’s really nice that they were able to come here today and tell us that it’s ok to not be ok."

After launching the summit, the prince will head to a military rehabilitation centre in Kaduna.

Prince Harry and Meghan were invited by Nigeria's chief of defence staff, General Christopher Musa, and will meet injured service personnel.

The duke and duchess will also visit Lagos.

The couple are set to attend a training session for Nigeria: Unconquered - a charity which collaborates with the Invictus Games - as well as a cultural reception and a polo fundraiser for the charity.

Meghan is also due to co-host an event of Women in Leadership with Dr Ngozi Okonjo-Iweala, director-general of the World Trade Organisation (WTO)

The couple's visit comes after the duke celebrated the 10th anniversary of the Invictus Games at St Paul's Cathedral in London on Wednesday.

He smiled and waved at a crowd gathered in the sunshine outside St Paul's to greet him.

The service was attended by his uncle Earl Spencer - Princess Diana's brother.

Meanwhile, the King, whose cancer treatment is ongoing, met members of the public at a Buckingham Palace garden party a little over two miles away.

The two did not see each other, with the duke's spokesman saying the King's "full programme" prevented any meeting.

The BBC was also given exclusive access to Prince Harry's final engagement during his short trip to London - he was a surprise guest at a party hosted by the charity Scotty's Little Soldiers, which supports the bereaved children of military personnel.