TRIPOLI, Libya — The Libyan government declared an immediate cease-fire Friday, but reportedly pressed in on rebel-held cities on two fronts, moves that U.S. officials quickly denounced as a violation of a U.N. resolution authorizing military force to protect civilians.

TRIPOLI, Libya — The Libyan government declared an immediate cease-fire Friday, but reportedly pressed in on rebel-held cities on two fronts, moves that U.S. officials quickly denounced as a violation of a U.N. resolution authorizing military force to protect civilians.

Moammar Gadhafi's government invited representatives from Malta, Germany, China and Turkey to the country to observe the "immediate cease-fire and stoppage of all military operations" it announced earlier in the day to widespread skepticism. "The door is open to any other country who wants to send observers," Deputy Foreign Minister Khaled Kaim told reporters, pledging that the foreign officials would be able to go "everywhere."

"The cease-fire means no military operation whatsoever, big or small," Kaim said.

It was not possible to immediately confirm whether Libyan armed forces halted their movement against rebel-held cities in the east and the west. But news trickling out of the battlefields suggested no cease-fire had taken hold.

In the east, Al-Jazeera television reported that Gadhafi's forces were advancing quickly on the rebels' de facto capital, Benghazi, and had gotten to within 30 miles of the city. In his comments, Kaim appeared to acknowledge movement of government forces toward Benghazi.

"The armed forces are deployed outside Benghazi but there is no intention to enter the city," he said.

Though phone service to Benghazi and rebel-held Misrata in western Libya has been disrupted, unconfirmed amateur video footage broadcast on Al-Jazeera showed continued fighting in Misrata, which remains under a sea, land and air blockade.

A spokesman for the opposition in Misrata told the British Broadcasting Corp. that fighting continued in the city an hour after the cease-fire was announced.

U.S. officials said they had received credible reports that the violence was continuing. Susan Rice, the U.S. ambassador to the United Nations, told CNN that Gadhafi was already in violation of Thursday's Security Council resolution.

Libyan Foreign Minister Musa Kusa acknowledged that the resolution passed in New York late Thursday could result in armed intervention by foreign military powers, piercing the veil of optimism that has shrouded official public discourse in Tripoli over the past few weeks.

Gadhafi has insisted for days in interviews that the entire world supports him, except for a few nations such as France and Britain. He did not make any public comments Friday.

"It's very strange and unreasonable that the Security Council would allow the use of military power, and there are signs that this might indeed take place," Kusa told reporters. "This goes clearly against the U.N. charter and is a violation of the national sovereignty of Libya."

The U.N. resolution quickly had one major effect. Eurocontrol, which monitors aviation traffic, disclosed that Libya had stopped all flights around the country, Reuters reported. Kaim said that Libya's air force has been "out of service" for the past two days.

While demonstrations in support of Gadhafi were staged in the capital on Friday, opposition activists were heartened by the Security Council vote, which they long have advocated to stop Gadhafi's air force. "Now we can face him man to man," said one opposition supporter.

Though Kusa said Libya took "great interest in protecting civilians and offering them all necessary humanitarian aid," two U.N. teams that have visited have been unable to break free of government officials to independently verify humanitarian conditions in conflict zones.

International aid organizations such as Doctors Without Borders have been not been allowed to enter Libya.