LONDON (AP) — British Prime Minister Boris Johnson and Prince Harry touted the U.K. as an ideal business partner for Africa on Monday as their country prepares for post-Brexit dealings with the world.

But Britain faces tough challenges as it seeks to assert itself on a continent with several of the world's fastest-growing economies and whose youthful 1.2 billion population is set to double by 2050.

Far fewer of Africa's 54 heads of state or government are attending the first U.K.-Africa Investment Summit than the dozens who attended the first Russia-Africa summit last year or the gatherings China regularly holds.

The U.K.'s department for international trade says two-way trade with Africa in the year ending in the second quarter of 2019 was $46 billion. Meanwhile, Africa's two-way trade with China, the continent's top trading partner, was $208 billion in 2019.

Johnson told attendees the conference "is long overdue." He acknowledged that British officials and companies needed to work to convince African nations to do business with the U.K.

"We have no divine right to that business," he said. "This is a competitive world. You have may suitors" — especially China and Russia.

Britain is due to leave the European Union on Jan. 31, and Johnson said the U.K. would become a free-trading "global Britain after Brexit."

He pledged that the post-Brexit immigration system would "put people before passports," acknowledging a common frustration across Africa.

While other global powers including Gulf nations and India have been increasing their diplomatic and economic presence in Africa, some observers have wondered about the interest of Britain, a former colonizer.

When Theresa May visited Kenya in 2018, even Kenyan President Uhuru Kenyatta noted it was the first visit to East Africa's economic hub by a British prime minister in more than three decades.

Britain said 16 African leaders were attending Monday's summit in London, including the leaders of Nigeria, Congo, Kenya, Egypt, Ghana, Senegal, Malawi, and Rwanda.

Aside from the sluggishness of its top two economies, South Africa and Nigeria, Africa is showing economic momentum as the recently launched African Continental Free Trade Area gathers steam.

Last year, economic growth slowed in all geographic areas except Africa, the United Nations reported last week in its annual World Economic Situation and Prospects 2020.

The U.N. said GDP growth in Africa is projected to reach 3.2% in 2020 and 3.5% in 2021. And 25 African countries are projected to achieve economic growth of at least 5% this year.

Over 80% of Britain's investment in Africa is focused on mining and financial services, and 30% of investment in the continent goes to a single country, South Africa, the Overseas Development Institute reported this month. Its report recommended a wider approach to Africa's growing middle class and increasingly sophisticated consumers.