A former CIA spy has revealed his key role in the arrest of Nelson Mandela, which led to the future South African president's trial and imprisonment for almost 28 years.

The bombshell disclosure led yesterday to a demand for the CIA to come clean about putting behind bars a figure who became one of the world's most revered statesmen.

A veteran political associate of Mandela called it a "shameful act of betrayal" that "hindered the struggle against apartheid".

The former CIA operative, Donald Rickard, was unrepentant, saying that when arrested in 1962 Mandela was "the world's most dangerous communist outside