Several air strikes and explosions shook Tripoli overnight in an escalation of an assault on the Libyan capital by the warlord Khalifa Haftar.

A Reuters reporter and several residents said they saw an aircraft circling for more than 10 minutes over the city late on Saturday, and that it made a humming sound before opening fire on several areas.

An aircraft was heard again after midnight, circling for more than 10 minutes before a heavy explosion shook the ground.

It was not clear whether an aircraft or unmanned drone was behind the blast, which triggered heavy anti-aircraft fire. Residents had reported drone strikes in recent days, but there has been no confirmation. Explosions heard in the city centre this time were louder than in previous days.

Residents counted several missile strikes, one of which apparently hit a military camp of forces loyal to the UN-recognised government, in the Sabaa district in the south of the capital – scene of the heaviest fighting between the rival forces.

Authorities closed Tripoli’s only functioning airport, cutting air links to a city with an estimated 2.5 million residents. The airport in Misrata, a city 200km to the east, remained open.

Haftar’s Libyan National Army (LNA) started an offensive to take the capital two weeks ago but has been unable to breach the government’s southern defences.

If a drone strike was confirmed, this would point to more sophisticated warfare for the group. The LNA has so far mainly used ageing Soviet-made jets from the air force of the former dictator Muammar Gaddafi, lacking precision firepower and helicopters, according to residents and military sources.

In the past, the United Arab Emirates and Egypt have supported Haftar with air strikes.

Heavy clashes

The air strikes, which were also filmed by residents and posted online, came after a day of heavy clashes in Tripoli’s southern districts, with shelling audible in the city centre.

The violence spiked after the White House said on Friday that US president Donald Trump spoke by telephone with Haftar earlier in the week.

The disclosure of the call and a US statement that it “recognised Field Marshal Haftar’s significant role in fighting terrorism and securing Libya’s oil resources” has boosted the commander’s supporters and enraged his opponents.

Western powers and the Gulf have been divided over the push by Haftar’s forces to seize Tripoli, undermining calls by the UN for a ceasefire.

Both sides claimed progress in southern Tripoli on Saturday, but no further details were immediately available. A Reuters TV cameraman visiting the southern Khalat Furgan suburb heard heavy shelling but saw no apparent change in the frontline.

On Friday, two children were killed in shelling in southern Tripoli, residents said. The fighting has killed 227 people and wounded 1,128, the World Heath Organisation said before the air strikes. – Reuters/Guardian