The French and German foreign ministers arrived in Libya on Saturday for unannounced talks with the head of the unity government Fayaz Seraj to offer support as he seeks to stabilise the North African state, a French diplomatic source said.

The visit by Jean-Marc Ayrault and Frank-Walter Steinmeier is part of efforts by the European Union to rebuild law and order in Libya and head off a potential new tide of migrants into Italy from the country, which has been in chaos since the toppling of long-time leader Muammar Gaddafi in 2011.

Western governments are also concerned about growing presence of Islamic State militants in Libya, where its affiliates have taken control of Sirte city and threatened oil installations as they seek to build a base beyond their Iraq and Syria territory.

"What's at stake is to get all the Europeans on the same page so that if there is a new anti-Islamic State coalition the Europeans speak as one voice and aren't faced with a US-Russian fait accompli like in Syria," said a French official.

The ministers, who will meet Seraj at a naval base in Tripoli where he has been operating the U.N.-backed Presidential Council, follow a visit by their Italian counterpart last week. The meeting also comes ahead of an EU foreign and defence ministers special dinner on Monday to discuss the situation in the oil producing nation.

The dinner is expected to agree to look into police and border training missions for Libya. Any such support would initially be in Tripoli, where the new government is trying to establish itself.

Seraj has been tasked with ending the country's political impasse, resolving its armed conflict and tackling a growing threat from Islamic State jihadists.

"There is no alternative to this government," said a senior French diplomat. "Seraj embodies the political solution. He has got a number of backers now and there is momentum, so we want to give this government a bit of spotlight."

An EU security presence in Libya, which would not involve soldiers, would be Europe's biggest step in the oil-producing nation since a Nato-backed mission led to the fall of Gaddafi in 2011.

Diplomats say there has yet to be detailed discussion with the new U.N.-brokered Libyan government in defining what kind of assistance it wants from the EU, and that the EU is keen to avoid the impression of moving into the country uninvited.

Seraj will brief the EU ministers by video conference on Monday.

"There hasn't been any request yet from Seraj," the diplomat said. "France isn't hostile to a military intervention, but it must be done through a Libyan request to the international community and it needs to be attached to the political process."

Paris played a leading part in the Nato air campaign that helped rebels overthrow Gaddafi, but has regretted the lack of support given to the authorities afterwards.

French aircraft are now conducting reconnaissance flights over Libya while French military advisers operate on the ground in conjunction with Britain and the United States.-Reuters