A French fighter jet has attacked and destroyed a Libyan military plane shortly after it landed at Misurate air force base, a French armed forces spokesman said.

The French warplane fired an air-to-ground missile at the Libyan jet after it breached the UN-imposed no-fly zone over Libya on Thursday.

The AP news agency cited an official earlier on Thursday as saying the Libyan plane may have been landing when it was attacked by a French Rafael fighter jet.

It comes as coalition forces continue to attack targets in the North African country in a bid to protect civilians from forces loyal to Muammar Gaddafi, the country's leader.

In a separate development, French fighter jets also struck an air base deep inside Libya, while NATO ships patrolled the coast to block arms and mercenaries entering the country.

Coalition bombers also struck artillery, arms depots and parked helicopters on Thursday. However the coalition bombardment has  failed to stop Gaddafi's forces from shelling opposition held towns.

More fighting

James Bays, Al Jazeera's correspondent in Ajdabiya, a key town about 125km away from the rebel stronghold of Benghazi, said he could hear missiles landing.

"We've heard four or five in the last 20 minutes or so. This is a city that has been pounded now for more than two weeks.

"I can tell you when you wander through this town there are very few residents here, most of them have fled, it''s like a ghost town.

Tony Birtley, Al Jazeera's correspondent in Benghazi, said opposition forces were "stuck" and unable to move forward.

"I think the reason for that is partly because they''re disorganised, partly because they don''t have the weapons and partly because Gaddafi's forces are very strong and have a lot of hardware," he said.

Al Jazeera has also heard that Gaddafi's forces have stepped up their attacks on the town of Zintan, west of the capital Tripoli.

A loud explosion was heard in Tripoli early on Thursday, and smoke could be seen rising from an area where a military base is situated.

"We heard another explosion just now. We see smoke rising. There are people on rooftops. It seems to be in a military area near the engineering college [in the Tajoura area]," one resident told Reuters news agency.

Libyan state television said Western planes had struck in Tripoli and in Jafar, southwest of the capital.

"Military and civilian targets were attacked by colonialist crusaders," the report said.

The US military said 14 Tomahawk missiles were launched overnight, while the US Africa Command in Germany said coalition forces also dropped bombs on targets.

Government officials have accused coalition forces of killing dozens of civilians,and some journalists were taken to a hospital early on Thursday morning and shown 18 charred bodies, which the government said were military personnel and civilians killed in the air strikes, Reuters reported.

But the US military officials deny any civilians have been killed in air strikes.

Undeterred by raids

The US military said it had successfully established a no-fly zone over Libya's coastal areas and had moved on to attack Gaddafi''s tanks.

The allies flew 175 sorties in 24 hours, and the US flew 113 of those, a US commander said.

Gerard Longuet, the French defence minister, said France had destroyed about 10 Libyan armoured vehicles over three days.

However, Gaddafi's tanks have rolled back into the town of Misurata under the cover of darkness, residents and opposition fighters said, resuming their attack after their guns were silenced on Wednesday by Western air raids.

The city, around 200km east of Tripoli and home to a major oil refinery, remains the last of opposition hold-outs in the west.

"Government tanks are closing in on Misurata hospital and shelling the area," a doctor in Misurata told Reuters on the phone before the line was cut off.

Source: Al Jazeera and agencies