Moammar Gadhafi's Libyan government is threatening to execute any citizen caught using a satellite telephone without official authorization.

The government announced the measure in the state-run JANA news agency as part of its campaign against rebels trying to oust the Libyan leader. It said unauthorized use of the phones amounted to treason.

The report says “spies” have been using the phones to pass information to NATO, which has carried out bombings that have killed “a large number of innocent civilians.”

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

Many Libyans have been relying on satellite phones because of the limited availability of mobile phone services in some regions of the country.

In a separate development Friday, opposition fighters say they have widened their gains in Brega, a strategic oil port that has changed hands several times since the start of the anti-government uprising in February.

But they say at least 11 rebel fighters have been killed in Brega in clashes with forces loyal to Mr. Gadhafi.

On Thursday, U.N. Secretary-General Ban Ki-moon expressed concern over the rising number of civilian casualties in the Libyan conflict.

In a statement, Thursday, he called on all sides to “exercise extreme caution in their actions, in order to minimize any further loss of civilian life.” Ban also said that “a cease-fire linked to a political process” is the only possible way to achieve peace in Libya.

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