UN Secretary-General Antonio Guterres on Monday strongly condemned the military escalation and ongoing fighting in and around Libya's capital Tripoli, and asked for an immediate end to violence, Xinhua News Agency reported.

Nearly 2,800 civilians have fled violence in the city, according to the United Nations, since an eastern-based army led by General Khalifa Haftar launched a surprise assault last week which has left dozens dead.

Guterres "urges the immediate halt of all military operations in order to de-escalate the situation and prevent an all-out conflict," said a UN statement late on Monday.

He "strongly condemns the military escalation and ongoing fighting in and around Tripoli, including the aerial attack today by a Libyan National Army aircraft against Mitiga airport".

The oil-rich northern African country has been rocked by violent power struggles between an array of armed groups since the NATO-backed overthrow of former leader Muammar Gadhafi in 2011, Agence France-Presse reported.

The UN-backed Government of National Accord, or GNA, controls the capital, but its authority is not recognized by a parallel administration in the east of the country, backed by Haftar, AFP said.

"I make a very strong appeal to Libyan leaders and in particular to Haftar to stop all military activities... and to return to the negotiation table", the EU's foreign policy chief Federica Mogherini said after talks with EU foreign ministers.

The GNA said French President Emmanuel Macron spoke with its leader Fayez al-Sarraj, expressing his "total opposition to the offensive against the capital and the endangering of civilian lives".

The French presidency confirmed the call took place, without releasing details of the discussion.

Fresh airstrike

Ahmad al-Mesmari, a spokesman for Haftar's forces, claimed responsibility for Monday's airstrike against Mitiga airport, east of the capital, which targeted a military plane and a helicopter.

A spokesman for national carrier Libyan Airlines said the civil aviation authority decided "to suspend aerial traffic until further notice".

Haftar is a former Gadhafi military chief who has emerged as a major player in Libya's political struggle.

Having seized control of much of eastern Libya and buoyed by a series of victories in the desert south, he turned his sights on Tripoli, vowing to "cleanse" it of "terrorists and mercenaries".

His offensive threatens to plunge the country into a full-blown civil war and once again thwart diplomatic efforts to find a solution to Libya's woes, AFP said.

The United States has appealed for an "immediate halt" to combat operations. Russia on Monday urged "all sides to reject actions that could provoke bloodshed in battle and the deaths of civilians".

Agencies and Xinhua