Nearly 1,100 people have been reported killed since military strongman Khjalifa Haftar, based in eastern Libya, launched an offensive against the capital Tripoli on April 4.

"The European Union and its member states are united in demanding that all Libyan parties commit to a permanent ceasefire," EU foreign policy chief Federica Mogherini said.

The EU also urged the parties to return to a UN-brokered political process, Mogherini said in a statement issued in Brussels while she met ASEAN foreign ministers in Bangkok.

The EU and its 28 countries, she said, welcome UN envoy Ghassan Salame's ceasefire proposal for the upcoming Eid al-Adha holiday as well as his call to relaunch negotiations.

The EU has long supported the UN-recognised and Tripoli-based Government of National Accord (GNA) in a bid to restore peace and stability following the 2011 revolt that toppled Moamer Kadhafi.

His ouster occurred after EU countries Britain and France gave military support to anti-Khadafi rebels.

The EU has also worked for years with the GNA to curb the flow of migrants through a largely lawless Libya to Europe from sub-Saharan Africa.

The four months of fighting has complicated such cooperation.

Fighters loyal to the GNA have kept Haftar's self-styled Libyan National Army (LNA) at bay on the southern outskirts of the city.