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 Qaddafi’s fortified 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 antigovernment 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 Qaddafi’s compound,” he said. “I cannot just sit and watch this happen.”

In Tripoli, Musa Ibrahim, a spokesman for the Qaddafi 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. And to achieve their ends both want chaos in Libya, he argued, asserting that such outside forces had turned a small and peaceful protest movement into a dangerous armed force.

Addressing an incredulous audience of foreign journalists whom the Qaddafi 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.”