The U.S. government will begin testing anti-missile laser defense equipment on three airliners next month as Washington beefs up aviation security, USA Today newspaper has reported.

Northrop Grumman Corp and BAE Systems will install laser defense equipment on out-of-service aircraft before a decision is made about putting it on passenger planes.

The laser systems are designed to confound heat-seeking shoulder-fired missiles that have been used in the past by terrorists trying to down passenger planes.

The result of the trials, which will be conducted by the Department of Homeland Security's systems engineering and development office, will be forwarded to Congress next year for review.

Officials have said installing such systems on all 6,800 aircraft in the U.S. passenger airline fleet would cost at least $6 billion, which would be the most expensive security upgrade ever of U.S. aviation, USA Today said.

So far, no U.S. airliner has been shot down by a ground-launched missile fired by terrorists. Allegations have circulated that a Boeing 747, TWA flight 800, was downed by a Stinger missile over Long Island Sound on July 17, 1997. But U.S. authorities have always dismissed the allegations.

However, Homeland Security authorities take the possibility of such attempts being made in the future seriously.