Margaret Thatcher wrongly told MPs that a British Airways flight landed in Kuwait before the invasion by Iraq had begun, according to newly released files.

The documents show that officials believed it might have been possible to turn the flight away if the Foreign Office had warned the airline an Iraqi incursion was under way.

Flight BA149 landed in Kuwait in the early hours of August 2 1990 and within hours, more than 300 passengers and crew had been detained by invading Iraqi troops.

The Foreign Office has now released its files on the flight amid long-standing claims that the Government allowed it to go ahead, even though they knew of the danger it was in because it was carrying a Special Forces team it wanted to infiltrate into the country.

The papers include an exchange of correspondence from September 1992 between the then prime minister Sir John Major and John Prescott, then the shadow transport secretary, who had been pressing for details of what happened.

In his reply, Sir John insisted there were no British military personnel on board the flight.

He also said that while Iraqi troops had been massing on the border there was no “firm evidence” that Saddam Hussein was about to invade, still less occupy, the whole of Kuwait.

However, a briefing note prepared by PM Nixon, an official in the Foreign Office Middle East Department, disclosed that the Government was being less than frank about what it new about the Iraqi troop movements.

“We have never made public the fact our ambassador in Kuwait telephoned the (Foreign Office) resident clerk before BA149 landed in Kuwait to say that Iraqi troops had crossed the border,” he noted.

“At the time, we had no reason to believe that the Iraqis would carry on and launch a full-scale invasion.

“The resident clerk did not inform the Department of Transport who might have been able to turn the flight away from Kuwait.”

Mr Nixon also expressed concern that when Mrs Thatcher answered questions about the flight in the Commons in the immediate aftermath of the invasion she may have misled Parliament.

The then prime minister said the flight landed and the passengers and crew disembarked before the invasion, adding: “The invasion was later.”

Mr Nixon wrote: “The then prime minister’s statement to the House of Commons on September 6 1990 may have given the impression that the aircraft landed before Iraqi troops crossed the border.

“This was not the case. The flight landed after the initial incursions but before the full-scale invasion was apparent.”