Obama shakes hands with Cuba's Raul Castro at Mandela memorial

US President Barack Obama on Tuesday shook hands with Raul Castro, leader of long-time Cold War foe Cuba, at the Nelson Mandela memorial service in Soweto.

Obama offered the handshake before taking the stage to give his speech at the ceremony, in a new sign of his willingness to reach out to US enemies, a US official told AFP.

The handshake was seen by millions around the world watching the memorial being broadcast live.

The handshake comes as Obama tries to make good on his vow to reach out even to the most implacable of US foes.

In September, the US leader spoke by telephone with Iranian President Hassan Rouhani, in the first such gesture since the 1979 revolution in the Islamic republic.

Cold War foes Cuba and the United States have had only limited ties for half a century, most of it under the iron fist rule of Raul's brother Fidel Castro.

Washington has maintained a trade embargo against Cuba for half a century, and the fate of the communist state is a bitter issue in US domestic politics.