The US and other world powers say they are ready to supply Libya's internationally recognised government with weapons to counter Isis and other militant groups gaining footholds in its lawless regions.
In a communique obtained by the Associated Press, the US, along with four other permanent UN Security Council members and more than 15 other nations say they are ready to respond to the Libyan government's "requests for training and equipping" government forces.
They are aiming to push for exemptions to a UN arms embargo imposed on Libya in a bid to keep lethal arms away from Islamic extremists and rival militias vying for power.
"The Government of National Accord has voiced its intention to submit appropriate arms embargo exemption requests to the UN Libya Sanctions Committee to procure necessary lethal arms and materiel to counter UN-designated terrorist groups and to combat Da'esh throughout the country," the communique said, using an alternate name for Isis.
"We will fully support these efforts while continuing to reinforce the UN arms embargo."
Foreign Secretary Philip Hammond tweeted he was in Vienna to take part in Libya talks to help the country fight Isis.
A British Foreign Office source added: "The focus of the meeting today is about capacity-building in the government and setting up the new government of national accord."
The source said talks were likely to cover issues such as the running of government ministries.
Sectarian war has been ravaging Libya since the fall of the former dictator Colonel Gaddafi in October 2011.
Rival governments in the east and the west have battled each other for dominance and in the chaos smaller groups, such as armed groups belonging to the country's Tuareg forces, have been able to carve out their own territories.
A Libyan branch of Isis was formed in November 2014 and has carved out territory along the northern coastline.
Last month, US President Barack Obama called the failure to prepare for Libya's future after the fall of Gaddafi the "worst mistake of his presidency".
Additional reporting by agencies
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