Theresa May will visit Nigeria later on the second day of her trade mission to boost ties with Africa after Brexit.
Mrs May will discuss security, trade and people trafficking with President Muhammadu Buhari before meeting victims of modern slavery in Lagos.
The prime minister already announced £4bn of extra British support for African economies during the first leg of her trip on Tuesday.
She also insisted her "sensible" Brexit plans will deliver a "good" deal.
Mrs May will travel to Abuja, the capital of Nigeria – Britain's second largest trading partner in Africa – for talks with President Buhari.
She is expected to announce a new UK and French project to help Nigeria and Niger strengthen their borders to crack down on trafficking.
The prime minister will also pledge to support victims of modern slavery who have suffered "enormous trauma".
Speaking ahead of her visit, she said the UK is a "world leader" in trying to end modern slavery.
The three-day whistle-stop trip is aiming to deepen economic and trade ties with growing African economies ahead of Britain leaving the EU in 2019./BBC/