Updated

The U.N. humanitarian coordinator for Libya has warned the country faces critical shortages of drinking water, food, fuel and medicine, following the six-month civil war between rebels and Muammar Qaddafi's forces that disrupted supply lines and damaged infrastructure.

The fighting has subsided in many area, including the capital Tripoli, since the rebels stormed in over a week ago, effectively ending Qaddafi's rule.

Since then, more than half a dozen U.N. agencies have returned to Tripoli to help with the country's humanitarian needs, the U.N. humanitarian coordinator for Libya, Panos Moumtzis, said late Thursday.

Panos said the U.N. has brought in 11 million bottles of water and will bring in 600 metric tons of food and 100 million euros worth of medicine. He warned, however, that he sees the U.N. aid as temporary.

"This country has a lot of resources and we view the humanitarian needs as short-term," he said. "I don't foresee the humanitarian program going beyond the end of the year maximum."

While rebel forces have seized most of the country, they have yet to capture Qaddafi or members of his family. Meanwhile, their forces have been advancing on the few remaining loyalist bastions.

In a fiery broadcast from hiding, Qaddafi warned late Thursday that loyal tribes in his main strongholds were armed and preparing for battle -- a show of defiance hours after rebels extended a deadline for the surrender of the fugitive leader's hometown of Sirte.

Rebel commanders have been negotiating with tribal leaders in Qaddafi's hometown of Sirte, hoping to avoid further bloodshed. They announced Thursday that they had extended the negotiations' deadline for another week, from this coming Saturday.

"We want to save our fighters and not lose a single one in battles with Qaddafi's forces," said Mohammed al-Rajali, a spokesman for the rebel leadership in the eastern city of Benghazi.

"In the end, we will get Sirte, even if we have to cut water and electricity" and let NATO pound it with airstrikes, he said.

The rebels have been hunting for Qaddafi since he was forced into hiding after they swept into Tripoli on Aug. 20 and gained control of most of the capital in subsequent days of fierce fighting.

"We won't surrender again; we are not women. We will keep fighting," Qaddafi said in a blustery tone in the audio statement, broadcast by Syrian-based Al-Rai TV. His voice was recognizable, and Al-Rai has previously broadcast statements by Qaddafi and his sons.

Qaddafi said the tribes in Sirte and Bani Walid are armed and "there is no way they will submit." He called for continued resistance, warning "the battle will be long and let Libya burn."

In a second late-night audio, also broadcast on the Syrian channel, Qaddafi spoke in more measured tones and called for a long insurgency. "We will fight them everywhere," he said. "We will burn the ground under their feet."

He said NATO was trying to occupy Libya and steal its oil.

"Get ready to fight the occupation. ... Get ready for a long war, imposed on us," Qaddafi added. "Get ready for the guerrilla war."

He also called Sirte "the capital of the resistance."

The rebels dismiss the threats as empty rhetoric. They believe Qaddafi may be in one of their three key targets: Sirte, Bani Walid, which lies 90 miles (140 kilometers) southeast of Tripoli, or the southern city of Sabha.

Backed by NATO airstrikes, the rebels are pushing toward those three targets.