The two South Africans held by Zimbabwean police on suspicion of being part of an attempt to assassinate President Nelson Mandela during his recent Zimbabwe state visit were innocent and no assassination plot existed, diplomatic sources said on Tuesday.

The pair, believed to be backpackers, were picked up by over-suspicious police in a routine security sweep before Mandela arrived in the midlands town of Kwekwe. A South African diplomatic official in Harare said: "From our point of view, there was no threat to the president's life. There was no assassination attempt at all."

South African high commission officials and Mandela`s security officers were told of the incident. "There were no arrests, so there was no need for a formal communication."

TUESDAY, 8.00AM

TWO white ex-South Africans were arrested in the Zimbabwe midlands town of Kwekwe shortly before the visit by Nelson Mandela last week, accused of being involved in an assassination plot against him and Zimbabwean president Robert Mugabe.

Assistant commissioner Philip Mhike on Monday confirmed the arrest of two men, who have since been released. But Mhike said the investigations were continuing around the country and that "any people responsible for this attempted assassination will be brought to book."

South African diplomats in Harare expressed surprise at the news, saying they had not been informed of any assassination attempt, or of the detention of any South Africans, as they would expect to be.