|The opposition remains defiant, saying it would not negotiate with Gaddafi to end the violence [Al Jazeera]
Forces loyal to longtime Libyan leader Muammar Gaddafi have shelled Misurata, pressing their siege of the embattled western city.
Four children were killed in the shelling on Tuesday, a resident named Mohammed Ahmed told the Reuters news agency. The children were killed while trying to flee their home, a rebel spokesman told Al Jazeera.
Gaddafi's regime has encircled Misurata for days, bringing in tanks and stationing snipers on rooftops, in an attempt to choke off one of the only cities in the west where a strong rebel presence remains. Shelling there killed at least 40 people on Monday, Ahmed said.
Misurata lies around 200km east of Tripoli, the capital, and is home to a major oil refinery.
Libyan government spokesman Ibrahim said Misurata, Libya's third-largest city, was "liberated three days ago" and that Gaddafi's forces were hunting "terrorist elements".
But a spokesman for opposition fighters in the city told the AFP news agency that the opposition remained in control despite an onslaught by Gaddafi loyalists, who he said opened fire with tanks and set snipers on roofs to gun down people in the streets.
"Casualties fell in their dozens," after snipers and a tank "fired on demonstrators", the spokesman said.
The opposition spokesman said Gaddafi's troops "have taken up position along the main road where they have deployed three tanks, as well as positioning snipers on rooftops".
Meanwhile, a US F-15 jet crashed in Libya late on Monday, reportedly due to a technical fault during a raid against anti-aircraft defences.
The US Africa command said on Tuesday that both its crew ejected safely. A command spokeswoman told AFP news agency that the crash was not a result of hostile action and an investigation to determine the cause
of the malfunction was underway.
There was also fierce fighting further east in Ajdabiya. Opposition fighters were seen retreating in the face of an attack by government forces.
Al Jazeera's Tony Birtley, reporting from an area close to Ajdabiya, said there had been clashes outside the city.
"There's been heavy fighting and heavy shelling going on ... the rebels told me there have been heavy casualties and there are a number of corpses between here and the town [of Ajdabiya] that they have been unable to reach."
He said the road between the eastern city of Benghazi and Ajdabiya was littered with the "burned-out wreckage of what was Gaddafi's armour and tanks," destroyed in air raids by coalition forces.
Government troops retreated 100km from Benghazi, the opposition stronghold, after fierce strafing by coalition aircraft destroyed much of their armour, the AFP news agency reported.
Meanwhile, around 106km south of Tripoli, Libyan pro-democracy fighters forced government troops to withdraw from the outskirts of Zintan, breaking a siege of the town.
After enduring heavy shelling the day before, rebels on Tuesday pushed pro-Gaddafi troops out of the eastern outskirts of the city, a Swiss journalist, Gaetan Vannay, told Al Jazeera.
Gaddafi's forces withdrew around 10km east, to a village that is still controlled by Gaddafi, he said.
During their push, rebels managed to capture four regime tanks, Vannay said. The international military coalition that is enforcing a no-fly zone over Libya did not aid the rebels by launching air strikes against Gaddafi's forces.
Calls for ceasefire
Meanwhile, international criticism of the coalition enforcing the no-fly zone has grown, with India joining China in publicly calling for an end to the strikes that have crippled Libya's air defences, destroyed regime forces on the ground and given rebels room to recover after nearly losing Benghazi, their stronghold in the east.
Jiang Yu, a spokeswoman for China's foreign ministry, said on Tuesday that the government opposed "the wanton use of armed force leading to more civilian casualties and more humanitarian disasters". China had already called for a ceasefire.
S M Krishna, the Indian foreign minister, called for a "cessation of armed conflict". His office had already issued a statement on Monday expressing "regret" for the military intervention.
Pranab Mukherjee, the country's foreign minister, said in a speech to parliament that "no external powers" should interfere in Libya.
"Nobody, not a couple of countries, can take that decision to change a particular regime," he said.
China and India were among five countries that abstained from the UN Security Council vote that approved Resolution 1973 authorising the no-fly zone and military intervention.
Turkey, which is not on the Security Council but is a key member of NATO, the Western military alliance, warned on Tuesday that it could not agree to NATO taking over the enforcement of the no-fly zone if their mission went "outside the framework" of the UN decision.
The calls for ceasefire came after coalition warplanes hit targets across Tripoli for a third night and anti-aircraft fire lit up the sky. Two large explosions could be heard about 10 minutes apart shortly after 9pm, said Al Jazeera's Anita McNaught, reporting from the capital.
She said two naval installations just outside the city, one of them thought to be the Abu Sitr Naval Base, had reportedly been hit in the strikes.
"We could see an area of the port on fire, substantially on fire, two big blazes. We saw fire engines racing along the coastal road," she said.
"This evening seems to have been about targeting seaborne military assets of Gaddafi's army, but also we are given to understand [there was] an attack on the airport at Sirte."
As fighting raged in Misurata, international coalition forces reportedly struck radar installations at two air defence bases belonging to Gaddafi's forces in Benghazi in eastern Libya.
The developments came as the UN Security Council rejected a Libyan request for an emergency meeting to halt what it called "military aggression" by coalition forces three days after they began launching strikes aimed at disabling Libyan air defences.
The council decided instead to hold a briefing already planned for Thursday to give a briefing on the coalition air campaign to Ban Ki-moon, the UN secretary-general.