Major powers including the US discussed in Vienna on Monday the growing threat posed by the Islamic State group in conflict-wracked Libya, just across the Mediterranean from Europe.

IS has taken advantage of the chaos left by the toppling and death of longtime dictator Moamer Kadhafi in 2011, which left rival militias vying for control of the oil-rich country.

A recently formed unity government backed by the international community has been slowly asserting its authority in Tripoli, but it still faces a rival administration in the east.

In a bid to stabilise the country, the fledgling regime of Prime Minister Fayez al-Sarraj has drawn up a list of requests for Western partners to assist its forces with arms, training and intelligence.

The Vienna conference, under way since 1215 GMT, is being co-chaired by the United States and Italy, Libya's former colonial ruler which has faced a major influx of migrants from the North African nation braving the perilous sea voyage.

A total of 25 top diplomats were in attendance, including the UN's special envoy to Libya Martin Kobler and EU foreign policy chief Federica Mogherini.

‘The key question is whether Libya remains a place where terrorism, people-smuggling and instability continue to flourish or whether we can regain statehood with the new unity government,’ German Foreign Minister Frank-Walter Steinmeier said.

‘We have a lot to do,’ US State Secretary John Kerry told reporters before he held brief talks with Sarraj at Vienna's plush Bristol Hotel.

- 'No boots on the ground' -

The Libyan leader has insisted his country needed assistance, not intervention.

‘We are not asking for foreign boots on the ground, but we are requesting assistance with training, and lifting the arms embargo on Libya,’ Sarraj wrote in a column published in the British newspaper The Telegraph on Monday.

Formed in late March, his Government of National Accord (GNA) has won international support as well as backing from key institutions like the central bank and the National Oil Corporation.

But it has failed to get the endorsement of the elected parliament and its ally Khalifa Haftar, a self-declared army chief who has launched a crusade against Islamist fighters across the country.

A rival government in the eastern city of Tobruk has also refused to recognise the GNA.

Amid the chaos, IS has carved itself a bastion in Libya where it overran last year the Mediterranean coastal city of Sirte, Kadhafi's hometown, transforming it into a training camp for militants.

Europe fears the jihadists, who have in recent weeks made new advances, will use Sirte's port and airport as a springboard to launch attacks on the continent.

IS ‘is a threat not only to Libyans and the wider region, but also to Europe,’ warned French Foreign Minister Harlem Desir at the start of Monday's conference.

‘We are calling on Libyan political powers to form an alliance with Sarraj and create the necessary institutions to combat (IS).’

The warnings have also struck a chord with Washington, where officials say plans are being drawn up to loosen an arms exports ban imposed five years ago by the UN.

A senior US administration official told AFP that Libya's international partners were willing to help if the GNA presented a ‘detailed and coherent list’ of what it needs to fight IS.

‘There is a very healthy desire inside of Libya to rid themselves of (IS), and I think that is something we should be supporting and responding to,’ the official said.

But diplomats have warned that the GNA may struggle to come with a concrete request for help.

- Race for Sirte -

Libya's divisions have once again deepened in recent days, with the GNA and Haftar's forces each announcing their own plans to fight IS and ‘liberate’ Sirte.

‘This is a mistake. It must be prevented... we can no longer accept this division,’ said Nicola Latorre, chairman of the defence committee of the Italian senate and an IS expert.

Claudia Gazzini, a Libya analyst at the International Crisis Group, has also warned that the race for Sirte is pushing any hope of a political solution further away.

IS is estimated to have around 5,000 fighters in Libya, and it is trying to enlist hundreds more.

This month the jihadists launched suicide attacks on key checkpoints in government-held territory along the Mediterranean coast.

The move allowed them to build a defensive line along part of the coastal highway that links the east of Libya where Haftar is based with Tripoli in the west.