US President Barack Obama and his wife Michelle will attend a South African national memorial service Tuesday in honor of late civil rights icon Nelson Mandela, a White House official said.

It was unclear whether Obama would stay through December 15, when Mandela receives a state burial at his boyhood home of Qunu.

The memorial service, at Johannesburg's 94,000-seat soccer stadium, comes ahead of the funeral, which will see a cortege with Mandela's coffin pass through the streets of Pretoria on three consecutive days.

Presidents, religious leaders and cultural figureheads from all corners of the world are expected for the funeral.

"The president and Mrs Obama will be attending the national memorial service for former president Mandela on Tuesday in Johannesburg," the official said, adding that further details would be provided later.

The White House has indicated that former first couple George W. and Laura Bush will accompany the Obamas on the presidential plane Air Force One.

Ex-president Bill Clinton, who was in office when Mandela took power to become South Africa's first black president, also said that he would be making the trip with his family.

The White House invitation was extended to Bush's father former president George H.W. Bush as well, but the 89-year-old declined since he can no longer travel long distances.

South Africa has declared a period of mourning for all of next week, starting Sunday with a "national day of prayer and reflection."

In a tribute shortly after the revered statesman's death was made public, Obama mourned Mandela as a "profoundly good" man who "took history in his hands and bent the arc of the moral universe towards justice."

Obama, who ordered flags to fly at half-staff at the White House and public buildings, said Mandela "transformed South Africa and moved all of us" in his journey from prisoner to president.

America's first black president met Mandela only once -- in 2005 when he had just become a senator -- but said he was inspired to enter politics by the anti-apartheid hero's example.