But the rebels dismissed the attacks as ineffectual, and Colonel Gaddafi faced a growing international campaign to force him from power, as the Obama administration announced it had seized $30 billion in Libyan assets and the European Union adopted an arms embargo and other sanctions.
As the Pentagon began repositioning Navy warships to support a possible humanitarian or military intervention, Secretary of State Hillary Rodham Clinton bluntly told the Libyan leader to surrender power "now, without further violence or delay."
The attacks by the colonel's troops on an oil refinery in central Libya and on cities on either side of the country unsettled rebel leaders -- who have maintained that they are close to liberating the country -- and showed that despite defections by the military, the government may still possess powerful assets, including fighter pilots willing to bomb Libyan cities.
Rebel leaders said the attacks smacked of desperation, and the ease with which at least one assault, on the western city of Zawiyah, was repelled raised questions about the ability of the government to muster a serious challenge to the rebels' growing power.
In an interview with ABC News, Colonel Gaddafi said he was fighting against "terrorists," and he accused the West of seeking to "occupy Libya." He gave no hint of surrender. "My people love me," he said. "They would die for me."
Those unyielding words, and the colonel's attacks on Monday were met with both nerves and defiance by rebel military leaders as the two sides seemed to steel themselves for a long battle along shifting and ever more violent front lines.
The anti-government protesters, who started their uprising with peaceful sit-ins but have increasingly turned to arms to counter Colonel Gaddafi's brutal paramilitary forces, have promised a large military response that has yet to come. At the same time, government forces have been unable to reverse the costly loss of territory to a popular revolt that has brought together lawyers, young people and tribal leaders.
Across the region, the tumult that has already toppled two leaders and threatened one autocrat after another continued unabated on Monday. In Yemen, protests drove President Ali Abdullah Saleh to make a bid for a unity government, but the political opposition quickly refused. An opposition leader, Mohamed al-Sabry, said in a statement that the president's proposal was a "desperate attempt" to counter major protests planned for Tuesday.
In Bahrain, protesters blocked access to Parliament, according to news agencies. In Oman, whose first major protests were reported over the weekend, demonstrations turned into violent clashes with the security forces in the port city of Sohar, and the unrest spread for the first time to the capital, Muscat.
Libya itself seemed to be brewing a major humanitarian crisis as tens of thousands of mostly impoverished contract workers tried desperately to flee to its neighbours, Tunisia to the west and Egypt to the east. The United Nations refugee agency called the situation a humanitarian emergency as workers hauling suitcases stood in long lines to leave Libya, many of them uncertain how they would finally get home.
The country they left behind faced similar uncertainty, as warplanes took to the sky for the first time in 10 days, according to military officials allied with the rebels. In a direct challenge to claims by those officials, who have asserted that Libyan Air Force pilots were no longer taking orders from Colonel Qaddafi, two Libyan Air Force jets conducted bombing raids on Monday, according to witnesses and two military officers in Benghazi allied with the anti-government protesters.
Col. Hamed Bilkhair said that the jets, two MIG-23s that took off from an air base near Colonel Qaddafi's hometown in the city of Surt, struck three targets, but were deterred by rebel antiaircraft fire from striking a fourth at an air base in Benghazi. The jets -- a bomber and an escort plane -- attacked three other locations, south of Benghazi, and on the outskirts of the eastern city of Ajdabiya.
Colonel Bilkhair said that a weapons depot was struck, but that the other strikes -- including one on a water pipeline -- were "ineffective." It was not clear whether there were any casualties, and the airstrikes could not be independently verified.
The colonel said that government Special Forces took control of the oil refinery at Ras Lanuf on Monday, though he and other rebel leaders played down the significance of the assault, saying the refinery was only lightly guarded. "It was only briefly occupied," by the rebels, Colonel Bilkhair said. "They occupied it for four days, and they had no weapons."
In Zawiyah, a city with important oil resources just 30 miles from the capital, residents said they rebuffed a series of attacks on Monday, suffering no casualties but killing about 10 soldiers and capturing about a dozen others. A government spokesman confirmed the death toll.
"It is perfect news," said A. K. Nasrat, 51, an engineer who is among the rebels, before adding, "There is no way they are going to take this city out of our hands unless we all die first."
The first attack took place shortly after midnight, when some pro-Gaddafi soldiers in pickup trucks tried to pass through the city's eastern gate, Mr. Nasrat said. But they were spotted by rebel sentries who defeated them with help from army and police defectors defending the town. Four soldiers were killed and several captured, with some of the captives readily surrendering their arms and switching sides, he said.
Then, in the early evening, several witnesses said, the Gaddafi forces -- believed to be led by his son Khamis's private militia -- attacked from both the east and the west. Three pickup trucks tried to enter the narrow city gates from the west, but a rebel-held artillery unit struck one, blowing it up and overturning a second truck, Mr. Nasrat said. Six more pickup trucks tried to breach the eastern gate, he said, but after an exchange of fire the rebels captured two of the trucks and several of the soldiers.
"So about 12 or 14 soldiers were hostages," he said, "and 8 of them turned over their arms and joined the people. They are on our side now."
At about 11 p.m. residents of Zawiyah reported in telephone interviews that they heard a renewed outbreak of gunfire from the west lasting 5 to 15 minutes, suggesting that sporadic attacks might continue through the night.
For days, military leaders in Benghazi have said they are preparing to assemble a force of thousands to conduct a final assault on Tripoli; some of the officials have even promised to send planes to bomb Colonel Gaddafi's compound, Bab al-Aziziya.
But there are few signs that a plan has materialized, though military leaders maintain they are simply waiting for the right time. A fighter pilot sympathetic to the anti-government protesters, Mohammed Miftah Dinali, expressed some frustration that he had not yet been called on to aid the rebel effort.
"My friends and I are willing to go and do an airstrike on Gaddafi's compound," he said. "I cannot just sit and watch this happen."
In Tripoli, Musa Ibrahim, a spokesman for the Gaddafi government, conducted a bizarre news conference in which he attributed the unrest in Libya to what he described as an alliance between radical Islamists and the Western powers. The Islamists want a Somalia-style base on the Mediterranean, and the West wants oil, Mr. Ibrahim said.
Addressing an incredulous audience of foreign journalists whom the government had invited to Tripoli, Mr. Ibrahim repeatedly denied that any massacres had taken place, contradicting the testimony of scores of Libyans in Tripoli and Benghazi.
Reporters told him that, on Sunday, when they visited Zawiyah, they saw no evidence of Islamist forces. "They knew you were coming," the spokesman said. "They were hiding those with an obvious Al Qaeda look."
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