Campaigners seeking to clear the names of the pilots blamed for the 1994 Chinook helicopter crash have threatened to disrupt parliamentary business.

Lord Chalfont, one of the leading campaigners, said the Ministry of Defence (MoD) "was not behaving under the rule of the law".

In a move designed to trigger a swift response, he said peers may amend legislation which gives parliamentary approval to Britain's armed forces.

The Royal Air Force Chinook helicopter crashed in thick fog on the Mull of Kintyre in June 1994 killing all 29 people on board.

Lord Chalfont: "Awful long time"

Flight lieutenants Richard Cook and Jonathan Tapper were found guilty of gross negligence by two RAF Air Marshals.

But in February a House of Lords select committee report concluded there were no grounds to blame the pilots.

Families and supporters of the airmen have called for the government to overturn the original MoD conclusions, but this has not materialised.

Lord Chalfont and his fellow campaigners are unhappy the MoD has so far failed to respond to this report.

Speaking on BBC Radio Scotland's Good Morning Scotland programme he said frustration was building over the delay.

'Rule of law'

He said parliament has to renew army, navy and air force acts to keep Britain's armed forces in existence.

"These acts have to be approved every year and this year approval has to be given by 31 August," he said.

"If approval was not given by this time then the air force and possibly the other two services would not be able to continue."

Lord Chalfont said the crucial issue was that of parliamentary sovereignty, and the government should respond.

Jonathan Tapper was blamed by air marshalls

"What I am trying to do is point out that the MoD in the case of the Chinook inquiry doesn't seem to be paying much attention to constitutional propriety.

"They are not behaving under the rule of law. All they have to do now is to set that verdict aside but they seem to be taking an awful long time about it."

Lord Chalfont said he had been assured a response would be made in time for the House of Lords to have a debate on the issue before the summer recess.

But this would not now be possible.

His amendment was not designed to harm the armed forces but to underline the importance of parliamentary sovereignty, he said.

"It (the amendment) is not something that anyone would want to carry to its conclusion unless the situation was very desperate."