As defence ministers from the 27 EU countries held video talks on the coronavirus pandemic's impact on European security, the bloc's foreign policy chief Josep Borrell renewed a call to halt the civil war raging in Libya.

The EU's new naval mission to block the flow of arms to Libya by sea got under way last week and Borrell -- in a statement issued in the name of all 27 countries -- vowed to make it work.

"The European Union remains determined to see the UN arms embargo in Libya fully respected," he said.

He said further efforts were needed to "ensure the full and effective implementation" of the embargo, particularly through Libya's land and air borders.

Libya has been mired in chaos since the ouster and killing of long-time dictator Moamer Kadhafi in 2011, with rival administrations in the east and west vying for power.

Operation Irini aims to halt the flow of arms into Libya, where the UN-recognised Government of National Accord (GNA) in Tripoli is under attack from the forces of strongman Khalifa Haftar, who controls swathes of the country's east.

Operation Irini now has a French frigate patrolling the eastern Mediterranean to look for arms shipments, backed up by aerial and satellite surveillance.

But critics have warned that by focusing on sea shipments, the new EU mission may deprive the Tripoli government of weapons but not Haftar, who receives supplies overland and by air.

On Sunday, the GNA said Haftar's forces had rained more than 100 rockets and missiles on residential areas in Tripoli, killing at least four civilians.

Borrell said that in view of the escalating violence, the EU was renewing its call for a truce.

"The European Union demands that all parties act responsibly and immediately cease the fighting all over Libya," he said in his statement.