PEOPLE might suspect somebody is hiding something about the RAF Chinook helicopter crash in which top security officials died, unless the Government declares the cause ''unknown'', a former Foreign Office minister warned last night.

Cross bencher Lord Chalfont, himself a former intelligence officer, was raising in the Lords for the fourth time the circumstances of the accident on the Mull of Kintyre in 1994 in which 29 people died.

He called on the Government to set aside the RAF inquiry verdict of ''gross negligence'' against the two dead pilots, Flight Lieutenants Jonathan Tapper and Rick Cook.

But Defence Minister of State Baroness Symons of Vernham Dean said, while the Government was ''more than willing'' to examine any new evidence, it still did not feel there was any reason to reopen the enquiry.

Opening a short debate on the issue, Lord Chalfont, backed by other peers, condemned the inquiry verdict as ''unjust and unjustified''.

He said: ''I am not suggesting that anything disreputable lies behind this tragic story but, unless the Government is prepared to put this matter right, others, perhaps less gullible than I, might suspect that somebody, somewhere is hiding something.''

Lord Chalfont referred to a Ministry of Defence document, disclosed by Computer Weekly magazine in July, which showed the Government in 1995 accepted the Fadec software to control the Chinook's two engines caused one helicopter to be destroyed during a ground test in the US in 1989.

He claimed this demonstrated ''there might have been other causes for the accident''. It was ''incomprehensible'' that the pilots were blamed, he declared.

Lord Chalfont, who was a Minister in the 1964-70 Labour Government, said the verdict had brought ''disgrace'' to the two young officers and ''lasting distress to their families''.

The Second World War veteran told peers: ''As an ex-soldier, I still sometimes find myself lying awake at night thinking about the bright and brave young men whose reputations have been destroyed by one of the worst accusations that can be levelled at a professional officer.''

The circumstances surrounding the accident were ''riddled with doubt in almost every aspect'', he claimed. ''The claim that there was no evidence of technical or computer malfunction does not mean that there was no malfunction.''

He called on Lady Symons to state categorically she was in possession of all the facts and ''there was absolutely no doubt whatsoever about the cause of this incident''.

Replying, Lady Symons said: ''The MoD has been consistently willing to examine new material. We remain more than ready to examine new material that offers new insights into the crash.''

She said if any peers still felt ''uneasy'' about the issue they could bring her their grievances.

Ruling out a reopening of the inquiry, the Minister stressed examination of the helicopters' engines showed they had both been running on impact. There was no sign of pre-crash failure. The MoD had examined the Computer Weekly material.

In addition, the Commons Defence Select Committee had published a report stating they had been unable to find any flaws with the Chinook or its components.

Earlier, RAF Marshal Lord Craig of Radley (Ind), a former Chief of the Defence Staff, said unless new evidence could be produced, the finding should stand.