Passengers reported to have been seen leaving terminal after strike by pro-Haftar forces

A warplane has attacked the only functioning airport in Tripoli as fighting between forces loyal to the Libyan warlord Khalifa Haftar and rival militias escalated and EU foreign ministers met in Brussels to try to de-escalate the violence.

Mitiga airport, in an eastern suburb of the capital, was closed after it was hit in an airstrike by pro-Haftar forces. Passengers could be seen leaving the terminal, a Reuters correspondent at the airport said. Fighting was also under way at Tripoli’s international airport, 15 miles from the city centre, which has not been functioning since fighting destroyed much of it in 2014.

The UN said 2,800 people had been displaced in an upsurge in violence that broke out after Haftar ordered fighters in his self-styled Libyan National Army (LNA), to march on the capital on Thursday.

The UN humanitarian coordinator in Libya, Maria do Valle Ribeiro, said the clashes had prevented emergency services from reaching casualties and civilians, and damaged electricity lines. The increased violence was also worsening the situation for migrants held in detention centres in Tripoli, she warned.

In Luxembourg the British foreign secretary, Jeremy Hunt, said the EU foreign ministers had reached a consensus that there was no military solution in Libya and that a UN peace process must be supported.

Q&A What is happening in Libya? Show Hide Libya is on the brink of an all-out civil war that threatens to upend years of diplomatic efforts to reconcile two rival armed political factions. An advance led by Khalifa Haftar, the warlord from the east of the country, has diplomats scrambling and the UN appealing in vain for a truce. The French government, the European power closest to Haftar, insists it had no prior warning of his assault, which is closing in on the capital, Tripoli. The outcome could shape not just the politics of Libya, but also the security of the Mediterranean, and the relevance of democracy across the Middle East and north Africa. For more about the fighting in Libya read our quick guide. Photograph: Hani Amara/X03394

Federica Mogherini, the EU external affairs chief, said the EU did not formally adopt a joint statement on Libya, but the members had been united in its appeal to all Libyan leaders, especially Haftar, to return to the negotiating table.

She appealed again for a ceasefire, but she accepted that the attack on the airport showed developments “are not going in the right direction”.

Libya is riven by two rival factions, one broadly supporting Haftar in the east and another based in Tripoli in the west including a UN-backed government led by Fayez al-Sarraj.

At least 27 people have been killed, including civilians, since Thursday, according to the health ministry of the Tripoli-based government. The media office for Haftar’s army said 22 troops had been killed.

A UK-led move to pass a security council statement condemning Haftar at the UN in New York on Sunday was blocked by Russia, which insisted all sides should be urged to show restraint. The UK draft would also have called “for those who undermine Libya’s peace and security to be held to account” and renewed support for a national conference to be held this month on holding elections.

In the wake of the Russian veto, the US secretary of state, Mike Pompeo, issued a statement identifying Haftar as the source of the problem.

“We have made clear that we oppose the military offensive by Khalifa Haftar’s forces and urge the immediate halt to these military operations against the Libyan capital,” Pompeo said. “Forces should return to status quo ante positions.”

The unrest in Libya deepened at the weekend after the government in Tripoli said it would launch a counter-attack against Haftar’s forces. The UN envoy for Libya, Ghassan Salame, said he met with Sarraj on Monday to discuss how the UN mission “can assist at this critical and difficult juncture”.

The UN refugee agency expressed anxiety about thousands caught in crossfire and detention centres in conflict zones in a “rapidly deteriorating humanitarian situation”.

Renewed civil war in Libya threatens to disrupt oil and gas supplies, trigger more migration to Europe, and allow Islamist militants to exploit the chaos. Over the weekend the LNA launched airstrikes on the south of the city as it sought to advance into the centre from the disused airport.

The Tripoli government has been run by Sarraj since 2016, as part of a UN-brokered deal boycotted by Haftar. The LNA, allied with a parallel eastern administration based in Benghazi, took the oil-rich south of Libya earlier this year before its surprisingly fast push towards the coastal capital. While that advance was straightforward, through mostly sparsely populated areas, taking Tripoli is a far bigger challenge.

Haftar has accumulated diplomatic support in Saudi Arabia, Egypt, the United Arab Emirates and parts of the French government.

French government sources insisted on Monday they had no prior knowledge of the Haftar assault on Tripoli, and denied France was privately trying to undermine the UN peace process.

The French officials insist they were ignorant of Haftar’s plan, a claim that is challenged by some Libyan observers who argue the French not only have have special forces embedded in the country, but have done more than any other European country to provide Haftar with international respectability. The French have argued that Haftar’s elite forces are a reality that simply cannot be ignored in a search for peace.

In the House of Commons, the British shadow foreign secretary, Emily Thornberry, called on France to “cease their support for Haftar’s assault on Tripoli”, remarks that are likely to anger the Élysée.

Mark Field, a Foreign Office minister, also urged Haftar to back down. And a succession of MPs urged the government to put pressure on the UK’s ally the UAE to end its support for Haftar’s actions.

Field, accepting the intervention in Libya in 2011 by the UK and others had led to calamitous consequences, pointed out that it was US influence in the recent past that had had a restraining effect on Haftar.