Updated

Libyan ruler Muammar al-Qaddafi's troops have boobytrapped petroleum installations in the strategic oil port of Brega so they can be blown up if his regime loses the town, a top rebel official said Thursday.

Mahmoud Jibril, the rebels' diplomatic chief, also said Qaddafi's forces have boobytrapped oil fields. He did not state which fields. While Brega is a key oil processing and shipment hub, the fields that feed it lie far to the south in the Libyan desert.

"Unfortunately, Brega is a big minefield right now," Jibril told reporters after meeting with Spanish Foreign Minister Trinidad Jimenez. "We discovered that they planted mines all over the place. Even some oil establishments, some oil fields, have been full of bombs, explosives."

Rebels hold most of eastern Libya, but their push to seize Brega since last week unraveled Tuesday when 27 rebels were killed in shelling by Qaddafi's troops.

Their forces have since pulled back from the city amid hopes that Qaddafi's forces will surrender, and Jibril said rebel fighters "are circulating Brega from all fronts right now." Rebel commanders have said mine fields laid by Qaddafi's troops have hampered their advance.

In Libya, local medic Mohammed Idris said a mine killed one rebel and injured four on Thursday.

Jibril said the boobytrapping of oil facilities and fields is a signal that Qaddafi's regime fears it can't hold Brega much longer "and the only course they have embarked on is to destroy everything."

Jibril also said that Libya's National Transitional Council wants foreign firms like Spanish energy company Repsol SA, which abandoned the country when fighting broke out, to return and rebuild their damaged installations -- and to allow Spain's government to deduct those costs from the frozen assets.

Last week's recognition of the council as Libya's legitimate government will potentially free up tens of billions of dollars in cash from frozen Libyan assets that the rebels desperately need, but Jimenez suggested that assets in Spain won't be immediately released.

Instead, she said Spanish officials and Libyan opposition officials will meet soon to determine whether the Spain assets could be used as collateral to provide the rebels with credit.

About $30 billion in Gahdafi-regime assets are frozen in American banks, and other countries hold billions more.

Jibril declined comment on the value of Libyan assets frozen in Spain, but said they consist of property, bank stock and other investments.

Libyan opposition officials have also been tracking down additional assets held around the world by people close to Qaddafi's regime, Jibril said. He characterized those amounts as a "flood" but did not provide amounts or describe them in detail.

"It seems that these assets in general, whether liquid or real estate, are mushrooming all over the place in Africa, Asia, Latin America" and Europe, Jibril said.

The effort to find more assets connected to Qaddafi's regime will continue so the opposition can try to claim "assets that belong to the Libyan people," he said.

Jibril's visit to Spain came a day after France's foreign minister suggested that a possible way out of Libya's civil war would be to allow Moammar Qaddafi to stay in the country if he relinquishes power.

Jimenez said Spain's position is that it is up to Libya's people to decide whether Qaddafi should stay or go, echoing comments issued a day earlier by the White House spokesman Jay Carney.

Qaddafi has insisted he will neither step down nor flee the country he has led for more than four decades.