WASHINGTON, Dec 30: The United States said on Tuesday that foreign airlines that refuse to place armed marshals on flights would be denied access to American airspace.

The move is part of a new US strategy to prevent Al Qaeda attacks inside the United States.

The Homeland Security Department said the new restriction had come into effect immediately. The decision marks a significant change in US aviation policy, as until now international security guidelines have been voluntary.

“Any sovereign government retains the right to revoke the privilege of flying to and from a country or even over their airspace,” said Homeland Security Secretary Tom Ridge. “So ultimately a denial of access is the leverage that you have.”

Agencies add: The International Air Transport Association (IATA) reacted cautiously on Tuesday to US demands that foreign airlines put armed guards on planes to meet terrorist threats, and said if the measure was obligatory governments must pay.

On Monday, US Homeland Security Secretary Tom Ridge issued an emergency directive that foreign airlines put armed police on flights where US officials deemed there was a terrorist threat.

“Our basic stance is that we do not want guns on board the aircraft, we certainly don’t want the cockpit to be armed,” said IATA spokesman Anthony Concil.

“If there are marshals on board the aircraft we ask that the captain be informed ... and we also believe that the governments need to pay for that ... the governments that are requiring it,” he said.

The announcement came eight days after US officials heightened a nationwide attack alert, citing intelligence that the Al Qaeda network wanted to stage an even bigger strike than the Sept 11, 2001, attacks.

The greater risk of a terrorist attack meant that airlines would go along with Washington’s demand, said the spokesman.