Libyan rebels say they have pushed closer to Tripoli by advancing on a town in a western mountainous region.

Rebels initially said on Saturday that they had seized the town of Gharyan, following clashes with forces loyal to leader Moammar Gadhafi.

Later in the day, the Associated Press quoted an opposition fighter as saying renewed clashes had erupted after pro-Gadhafi forces returned with reinforcements.

Gharyan is located about 100 kilometers from the capital.

On Friday, rebels reported gains on at least two other fronts. They said they had advanced farther into the strategic oil port of Brega and strengthened their hold in towns near Zawiya, a city west of Tripoli.

Meanwhile, a Libyan government official slammed U.N. chief Ban Ki-moon on Saturday for comments that that he made earlier in the week concerning civilian casualties.

On Thursday, Mr. Ban expressed concern about the rising number of civilian deaths and urged all sides to “exercise extreme caution.”

Deputy Foreign Minister Khaled Kaim said Saturday that Mr. Ban's remarks were “unacceptable” because they did not single out NATO as being responsible for civilian deaths.

On Tuesday, Libya accused NATO of killing 85 people in a village near the western town of Zlitan. NATO said its warplanes had hit targets in the area the previous day but denied evidence of civilian casualties.

Separately, Mr. Gadhafi's government has threatened to execute citizens caught using satellite phones without official authorization.

The crackdown was announced Friday in state-run media reports. Government officials said the move is designed to keep citizens from using the phones to aid NATO, which has been targeting government and military positions in airstrikes over the country.

NATO began launching air strikes against in March, supporting rebels who have been fighting against Mr. Gadhafi's 42-year rule.