NATO has insisted its bombing blitz in Libya is not aimed at Moamer Kadhafi, as explosions rocked the capital on Wednesday and rebels in besieged Misrata punched forward against the strongman's forces.
The rebel leader Mahmud Jibril was, meanwhile, set to meet with key US lawmakers on Wednesday to discuss the raging conflict which has left thousands dead and sent more than 750,000 people fleeing the north African country.
Explosions could be heard in eastern Tripoli for almost an hour on Wednesday morning as jets flew overhead, a witness told AFP.
The explosions began about 7:30 am (0530 GMT) and continued sporadically until 8:15 am (0615 GMT), the witness added.
NATO said that since the alliance took over military operations on March 31 to protect civilians from pro-Kadhafi forces, jets have conducted almost 6,000 sorties, including more than 2,300 strike missions.
Bombs were not dropped during all of those missions, figures showed, as officials insisted again the raids were not aimed at killing Kadhafi, who has ruled Libya for more than four decades.
"All NATO targets are military targets, which means that the targets we've been hitting, and it happened also last night in Tripoli, are command and control bunkers," Brigadier General Claudio Gabellini told reporters on Tuesday.
"NATO is not targeting individuals," he said via videolink from the operation's headquarters in Naples, Italy.
But asked whether Kadhafi was still alive, the Italian NATO general said: "We don't have any evidence. We don't know what Kadhafi is doing right now."
Jets had screamed in low over the capital, Tripoli, in a heavy bombardment lasting roughly three hours on Tuesday morning, an AFP correspondent said.
The blasts came after NATO chief Anders Fogh Rasmussen said time was running out for Kadhafi, who had to "realize sooner rather than later that there's no future for him or his regime."
Kadhafi survived a similar NATO bombing on May 1 in Tripoli, which killed his second-youngest son, Seif al-Arab, and three of his grandchildren.
Inspired by the uprisings in other Arab nations, rebels have been fighting since mid-February to oust Kadhafi but have met with stiff resistance despite gaining a foothold in the eastern city of Benghazi.
The rebels said they had driven Kadhafi's forces back from around the western port of Misrata, which has been under loyalist siege for some two months, and were poised to make another thrust.
After heavy clashes, the rebels controlled a stretch of coast road west of Misrata, their last major stronghold in the west, prompting thousands to flee.
An AFP correspondent said the rebels had forced government troops about 15 kilometers (10 miles) from Misrata, advancing to Dafnia, and were readying to move on Zliten, the next major town on the road to Tripoli.
Haj Mohammed, a rebel commander, said on Tuesday that "every day we manage to advance along the coastal road toward Zliten. Yesterday 15 kilometres (10 miles), today only two, but the advance is unstoppable."
Rebels were using shipping containers to shield themselves from loyalist fire, and bulldozers were pushing them forward as the advance continued.
Ahmad Hassan, a rebel spokesman in Misrata, said the insurgents had also "liberated" areas south and east of the city, killing many Kadhafi troops and seizing a large amount of weapons. Eighteen rebels and civilians were wounded.
The rebel claims could not be immediately verified.
They have set up a National Transitional Council (NTC) and Jibril, a senior figure in Libya's opposition, was to meet with key US lawmakers on Wednesday to discuss the conflict, senior US Senator John Kerry said.
Kerry, a Democratic ally of the White House who chairs the Senate Foreign Relations Committee, said he would make a public appearance with Jibril at 3:30 pm (1930 GMT).
"The Foreign Relations Committee and the American people are eager to learn more about the opposition movement in Libya and Mahmud Jibril is well positioned to answer our questions," Kerry said in a statement.
The United States has yet to recognize the NTC unlike France, Italy, Qatar and Gambia, with officials in Washington saying they wanted "a clearer picture" first about the opposition body.
Meanwhile, the UN refugee agency appealed to ships in the Mediterranean to treat all boats leaving Libya as being in need of assistance after reports that a vessel loaded with up to 600 people had capsized last week.
The office of the UN High Commissioner for Refugees said the number of flimsy and overloaded boats carrying people fleeing Libya was increasing.
"We believe that any boat from Libya should be considered at first glance as a boat that is in need of assistance," UNHCR spokeswoman Melissa Fleming said.
"We believe that all of these boats are carrying people who are trying to escape, many of whom are weakened by conflict, please do not wait for a call of distress."
The United Nations said Monday that nearly 750,000 people have fled Libya since the start of the conflict.