THE two RAF pilots flying the Chinook helicopter which crashed into the Mull of Kintyre four years ago have been wrongly blamed for causing the 29 deaths which resulted, an influential cross-party group of MPs claimed yesterday.

Senior defence experts from the three main parties urged the Government to reopen the investigation into the fatal crash in June 1994.

The casualties included 25 leading Northern Ireland anti-terrorism experts drawn from various security and intelligence forces.

The five MPs claimed to have tracked down new research proving that the RAF's board of inquiry should never have concluded that there was ''no possible doubt whatsoever'' that gross negligence by the pilots led to the crash.

They produced testimony from two aviation experts suggesting that pilot error was the least likely of four possible explanations for the helicopter's downfall. The mysterious crash could easily have resulted from a technical failure, they claimed.

Defence Secretary George Robertson should intervene and help clear the names of the two dead pilots, Flight Lieutenant Jonathan Tapper and Flight Lieutenant Rick Cook.

However, Armed Forces Minister Dr John Reid immediately dismissed the MPs' new dossier as ''a recycling of old theories'' and regretted that it had been put into the public domain before the Ministry of Defence had had the chance to study it properly.

The MPs insisted the RAF's verdict that the pilots had got things disastrously wrong on the flight over the Irish Sea into Scottish airspace amounted to ''a miscarriage of justice''.

It was impossible that the RAF could have been so overwhelmingly certain that there was no other possible explanation for the Chinook's crash into the cliffs near Campbeltown.

Conservative defence spokes-man Robert Key said all the five MPs believed an injustice had been done. ''We cannot accept that there is no possible doubt whatsoever about the cause of the crash.''

At a Westminster press conference, Chinook expert and retired senior RAF officer Squadron leader Robert Burke said there were several other plausible possible explanations.

In a detailed submission to Mr Key, the former RAF test pilot said the air force board of inquiry's conclusion blaming the pilots ''has so many anomalies that it is almost inconceivable for it to be correct''.

He advanced three explanations which he said were more likely to have been to blame than pilot error.

q A control jam, caused by a spring coming loose, which disastrously affected the Chinook's steering.

q An engine ''runaway'' caused by the helicopter's controversial FADEC computer system, which could have made the aircraft almost uncontrollable as it approached the Mull of Kintyre.

q An uncommanded flying control movement other than a control jam.

Mr Burke said that, after studying all the available evidence, he had come to the conclusion that the official conclusion of gross negligence was totally unfair and unjust.

''If you blame the pilots, virtually everything else you can gloss over as a cause of the accident,'' he said.

In his letter to Mr Key, the ex-RAF man said: ''Even someone like me with very limited knowledge of the workings of the MoD can work out very easily why a pilot error verdict was very convenient.''

Pressed to explain that remark, the former squadron leader strongly suggested that the authorities either did know or should have known about technical problems with the Chinook which could have caused problems.

If they had admitted after the crash to having had such knowledge, that could have dealt a blow to the war on terrorism in Northern Ireland.

Flight Lieutenant Tapper's father, Michael, said his son's name had been unfairly blackened by the RAF's internal inquiry. ''The reputation of any service officer is an important thing, particularly when it's a massive injustice like this,'' he said.

''These two were first-class pilots, some of the best in the world. To have this slur against their names is quite intolerable,'' he said.

Mr Menzies Campbell, the Liberal Democrats' defence spokesman, said he did not believe the evidence which the RAF had collected enabled them to condemn the two pilots as having been guilty ''with no possible doubt whatsoever''.

Mr James Arbuthnot, the former Armed Forces Minister, admitted he had wrongly given MPs misleading information about the crash when quizzed on the issue in Parliament last year.