TRIPOLI - The NATO bombing campaign that fatally weakened Muammar Gaddafi's rule had a secret asset: A 24-year-old Libyan woman who spent months spying on military facilities and passing on the details to the alliance.

The woman, operating under the codename Nomidia, used elaborate methods to evade capture - constantly changing her location, using multiple mobile telephone SIM cards and hiding her activities from all but the closest members of her family.

Her biggest protection against arrest by Gaddafi's security forces though was her gender: As a young woman in Libya's conservative Muslim society, they did not suspect her.

"I was not on the radar," the woman, an engineer, told Reuters in an interview in the lobby of a Tripoli hotel, two weeks on from a rebellion that broke Col. Gaddafi's control over the Libyan capital after 42 years in power.

"They were concentrating more on the guys and it was almost impossible to think that a girl was doing all of this."

Nomidia spoke to Reuters on condition that her real identity not be revealed: She said that while Tripoli was now under control of a new interim government, there was still a "fifth column" of Gaddafi loyalists who might target her or her family.

The account she gave of her activities was corroborated by two other people who were part of an underground anti-Gaddafi network and helped her send details about his security forces.

"[She was] a very important source, and very trusted," said Osama Layas, a forensic pathologist who was a member of the network.

When Nomidia began her undercover role five months ago, Col. Gaddafi and his security forces had a firm grip on the city and stifled any information that could be useful to his opponents.

A tall, slender woman with a green chiffon scarf draped over her head, Nomidia said she felt compelled to act after the brutal way in which Gaddafi's forces put down the first stirrings of revolt in cities around the country.

She began by calling Libya al-Ahrar, an anti-Gaddafi television station based in Doha, Qatar.

With little real information leaking out of Tripoli, producers at the station put her voice on air - under the name Nomidia - with accounts of what was happening in the city.

Soon she was dialling in with details of military forces, which the channel wanted to keep off the air to avoid alerting Gaddafi's government.

Instead they began passing on the information to NATO, via officials with the rebel government, the National Transitional Council (NTC), said Lina, at the time a producer at the station who was Nomidia's principal point of contact.

The information Nomidia upplied was "basically, where they were storing their arms,t heir tanks," said Lina, who sked to be identified only by er first name.

"She did an amazing job," Lina told Reuters by telephone.