The FBI's new embarrassment

Leung faces 50 years in prison if convicted

Although the charges against Katrina Leung, suspected of being a Chinese double agent, are damning, her supporters have been quick to say that she is no Mata Hari.

The 49-year-old naturalised US citizen is instead, they claim, a victim who has been "stabbed in the back" by the FBI officials who recruited her and then offered up as a "sacrificial lamb".

In a story that has, once again, embarrassed the nation's already beleaguered intelligence agency, Ms Leung is alleged to have had an affair with the FBI agent who recruited her to provide intelligence on China.

Instead, she is said to have performed a double cross, passing on information instead to the Chinese themselves.

Now Ms Leung, formerly considered a star intelligence source, is at the centre of one of America's biggest intelligence scandals, and may find little sympathy in a country already deeply concerned about national security following the 11 September attacks.

Glittering lifestyle

Ms Leung, born in China, moved to the US in the 1970s, obtaining an MBA from the University of Chicago before being recruited by FBI agent James Smith to spy on the country of her birth.

Leung's husband has said he will stand by his wife

Fluent in Mandarin and Cantonese and in a marketing job which frequently gave her cause to visit China, she may have seemed a perfect choice for the US intelligence organisation.

Based in California, the woman codenamed "Parlor Maid" by the FBI also became a well-known face on the state's social scene. She held lavish fundraising events for local Republican party politicians in her million-dollar house in a wealthy area of the southern city of San Marino.

But amidst this glittering lifestyle, Ms Leung is alleged to have had affairs with both Mr Smith and another FBI agent. She is also said to have passed on information taken from Mr Smith in the most simple way - by photocopying classified and highly sensitive documents he left in his unlocked briefcase.

Damning allegations

More damagingly the FBI, already struggling to cope with its perceived failure to prevent the 11 September 2001 attacks, may already have known that Ms Leung was working with, not against, the Chinese.

Intelligence sources have told the ABC network that FBI officials were informed 12 years ago that Ms Leung was a double agent.

The channel also reported that Ms Leung is suspected of telling the Chinese in 1998 how their consulates and embassy in the US had been bugged by the FBI with listening devices and miniature cameras placed in photocopying machines, paper shredders and other office equipment.

In 2001, it is alleged that she tipped off authorities in Beijing that the FBI had planted listening devices in the Chinese premier's Boeing 767 aircraft, the sources added.

Ms Leung, arrested on 9 April, now faces five charges - two counts of copying national defence documents and three of unauthorized possession of national defence documents.

She has not been charged with espionage, but if found guilty of the charges she faces she could receive up to 50 years in prison.