PRESSURE was growing on the Lord Advocate last night to step into the row over the planned release from prison of a key suspect in the Lockerbie bombing who is to be freed under a secret deal between the Iranian and German governments.

Dr Jim Swire, spokesman for the 270 victims of the disaster, said he firmly believed the man at the centre of the diplomatic row, Palestinian terrorist Hafez Dalkamoni and his gang, were the prime movers behind the bombing.

Dr Swire, who lost his daughter Flora in the Lockerbie disaster, said Dalkamoni should not be released from his German prison cell until a full investigation into his involvement in Lockerbie was carried out and a full team of Scottish police officers were allowed to interview him.

In light of the new developments Labour MP Tam Dalyell has written to the Lord Advocate, Lord Mackay of Drumadoon, making it clear that freeing Dalkamoni will seriously undermine efforts to find out who was responsible for the disaster.

Mr Dalyell's letter asks five questions of the Lord Advocate including whether he would talk to the German authorities before the release of Dalkamoni, whether the Germans had contacted Scottish police about his release, and whether the Government would now be in touch with the German government on the matter.

Dalkamoni and his accomplice, Abdel Ghadanfar, led a 14-strong Palestinian cell arrested in Frankfurt weeks before the disaster on December 21, 1988.

Dr Swire, who had made extensive inquiries into the case, said a tape recorder made into a bomb was found in the boot of Dalkamoni's car. The timing mechanism was set in motion by a drop in atmospheric pressure, conditions only to be found in an aircraft as it attains altitude.

Dalkamoni and Ghadanfar were held in custody but the other members of the cell were released and Dr Swire said he believed they were involved in planting a suitcase laden with explosives on the jet at Frankfurt airport.

Dalkamoni was finally jailed in 1991 for 15 years for trying to blow up an American military train but as part of the secret deal with Iran will be released soon after serving less than a third of his sentence.

His accomplice in the plot to blow up the train, Abdel Ghadanfar, who was also arrested at Frankfurt airport, was jailed for 12 years and released in secret last year.

The controversial German deal with Iran follows a visit by their intelligience chief, Ali Fallahian, to meet his German counterpart, Bernd Schmidbauer, in late 1993.

Last night Dr Swire and Mr Dalyell called for immediate action by the Lord Advocate to try and halt the release of Dalkamoni. Both said it was vital that he was interviewed by Scottish police.

Dr Swire said the Government claim that two Libyans were behind the bombing ``may well be codswallop''.

Despite the Government insistence of the case against the Libyan pair, he said he firmly believed that Dalkamoni and his gang were heavily involved in the bombing.

A Scottish Office spokesman said last night that once they had seen the contents of Mr Dalyell's letter they would respond to it.