Iran has rejected a call from the United States to co-operate in investigations into the 1996 bomb explosion which killed 19 American servicemen at Khobar in Saudi Arabia.

American officials had urged Teheran to co-operate in checking reports that three Saudi men involved in the attack had sought refuge in Iran.

The Iranian Foreign Ministry spokesman, Hamid Asefi, issued a curt rebuff to the latest appeal for co-operation from his American counterpart, James Rubin.

Mr Asefi described as "unfounded" American allegations that three Saudi Shi'ite Muslims belonging to an underground group called Saudi Hizbollah, had fled to Iran in the wake of the bomb attack at Khobar.

Clinton sent secret message to Iran

Accusing Washington of using intimidation and blackmail, the Iranian spokesman said the events had nothing to do with Iran.

The allegations, he said, were aimed at sowing division and discord between Teheran and Saudi Arabia, whose relations have improved dramatically over the past two years.

Iranian and American officials have confirmed that President Clinton last month sent a secret message to Iran's reformist president, Mohammed Khatami, in which he asked him to co-operate in the investigation and hinted that that could help speed up detente between the two countries.

They have been estranged since the Islamic revolution 20 years ago. But relations with the United States are a highly charged topic in Iranian politics.

It would be political suicide for an Iranian leader to open an initiative without a broad consensus behind him and that certainly does not exist at present.

So the Iranian response to President Clinton has been negative.