The West can no longer claim to be the dominant force in modern art, the director of the Tate museums has declared, after announcing a major shift towards acquiring and exhibiting the best new work from Africa, Latin America and the Middle East.

Sir Nicholas Serota yesterday pledged that Tate Modern will devote 40 per cent of its acquisition budget to securing important international works. The museum has bought its own Museum of Contemporary African Art, currently housed in Benin and featuring works spread across 12 rooms, which will be shipped to London and given its own wing next summer. A two-year project called Across the Board will start this month featuring shows by leading African artists, which will then tour to Ghana, Cameroon and Nigeria.

Sir Nicholas denied that Tate Modern was engaging in a new form of "cultural colonialism", stripping Africa of its most important works for the benefit of a London audience. "We're not removing the stuff," he said. "I don't want every Turner to be locked forever in this country. And I don't believe that most people who are engaged in art in Africa or the Middle East want the work to be locked in those places, not available, not known, and not part of international discourse. It was the failure to do so which meant museums like the Tate and the Museum of Modern Art in New York and the Pompidou Centre were much less rich in the 1960s and 1970s than they are now."

Africa rising: The Tate's new stars

Meschac Gaba Benin-born Gaba conceived the Museum of Contemporary African Art 1997-2002, now bought by Tate Modern, an ambitious collection of 12 rooms for an institution that "doesn't exist. It's only a question". He explores money as a bearer of cultural identity on his series of shredded banknotes.

Otobong NkangaMultimedia visual artist from Nigeria whose work questions the role of African women. She will invite the visitor to "engage in a performance about the shifting states of objects and tangible things" when she presents Contained Measures, an installation in the Tate Modern's new Tanks space.

Ibrahim El-SalahiFirst major UK exhibition for Sudanese painter who fled to Britain after being falsely imprisoned for conspiracy against the government. A significant figure in African modernism, his colourful work blends Islamic calligraphy, folk art and European elements.