The Alazan rockets, which have a range of eight miles, were among 50,000 tons of weapons left behind at an arms dump in the breakaway eastern European republic of Transdniester when the Russian army withdrew after the cold war.

They were offered to the reporter for $500,000 (£263,000) after he approached a senior officer in Transdniester’s secret police, claiming to represent a militant group in Algeria. The officer contacted a local arms dealer who arranged meetings with the reporter on a bridge in Transdniester and later at a hotel in neighbouring Moldova.

At their first meeting two months ago, the dealer said the price of a single rocket would be $200,000. The rocket could be independently inspected with a Geiger counter to verify that its warhead contained radioactive strontium and caesium, he said.

Last month the reporter was told that he would have to transfer $2,000 to a bank account in Cyprus before the inspection. He would then pay $8,000 for forged documentation that would enable the rocket to be smuggled across Transdniester’s border with Ukraine. It could be collected at an airfield in southwestern Ukraine once the rest of the asking price had been handed over.

Last week the dealer said that the terms had changed. “My people want to sell three Alazans for a total sum of $500,000,” he said.

According to the dealer, the rockets would be moved to Ukraine tomorrow if the terms were accepted. The Sunday Times withdrew from the negotiations once the availability of the weapons had been confirmed.

Experts said the Alazan rockets, which were originally intended for use in Soviet weather experiments, could spread radiation for more than 20 miles from their point of impact. Few people would die, they said, but the contamination would cause widespread fear and disruption. Large areas would have to be evacuated for a costly clean-up operation.

“The psychological impact would be devastating and the economic damage would run into millions of pounds, “ said Andy Oppenheimer, a consultant to Jane’s Information Group. “The Alazan would be especially attractive for terrorists seeking to strike a high security target.”

United Nations and regional officials are pressing for tighter security at the arms dump in Transdniester.

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