South African leaders congratulated US president-elect Barack Obama on his victory on Wednesday, expressing hope that it would place Africa's problems higher on the global agenda.

Obama became the world power's first black president as his Republican rival John McCain conceded defeat in historic elections on Wednesday morning.

President Kgalema Motlanthe sent "warm congratulations" to Obama.

"Your election to this high office of the American people carries with it hope for millions of your country men and women as much as it is for millions of people of particularly of the African descent both in the continent of Africa as well as those in the diaspora," Motlanthe said in a statement.

"We express the hope that poverty and under-development in Africa which remains a challenge for humanity will indeed continue to receive a greater attention of the focus of the new administration," added Motlanthe.

"A period of great change"

The ruling African National Congress said it expected South Africa to maintain its strong relationship of "mutual respect and co-operation" with the United States.

"The ANC is confident that the Obama administration will work to strengthen ties between the United States and Africa, building on development initiatives already in place, forging a genuine partnership to tackle the challenges facing the continent," said ANC spokesperson Jessie Duarte.

The Federation of Unions of South Africa (Fedusa) said Obama's election signalled "a period of great change in a world that desperately needs it".

"We are proud that seed from the African continent has risen to the highest office in the USA, and that an African will now be residing in the White House.

"We are truly elated by President Obama's election as president, and we hope that this will signal a time during which global challenges of unemployment and poverty will again become part of the world agenda", said Fedusa general secretary Dennis George in a statement.

Sapa