A truck bombing Thursday targeted a police training camp in war-torn Libya, causing at least 65 casualties and 200 wounded, according to hospital sources.

The truck crashed into the gate of the camp in the coastal city of Zliten, around 160 kilometres east of the capital Tripoli.

Health ministry spokesman Ammar Mohammed Ammar said 50 to 55 people had been killed and at least 100 wounded and that victims were being treated in several hospitals. Urgent calls were issued for blood donations.

Mayor Miftah Hamadi said the bomb detonated as recruits were gathering at the police centre in Zliten, a coastal town between the capital Tripoli and the port of Misrata.

Witnesses said residents were ferrying victims to Misrata hospitals in ambulances and cars, many with shrapnel wounds. Medical sources said 65 people had been killed, including some civilians, though one official said between 50 and 60 had died.

There was no immediate claim of responsibility for the attack but the Daesh terrorist group, which has been growing in power in Libya, has previously carried out many suicide bombings in the country.

The UN envoy to Libya, Martin Kobler, denounced the attack and called for national unity.

"I condemn in the strongest terms today's deadly suicide attack in Zliten, call on all Libyans to urgently unite in fight against terrorism," he wrote on Twitter.

Libya has been beset by chaos since the 2011 overthrow of longtime dictator Moamer Gadhafi and IS has been gaining influence.

The country has had rival administrations since August 2014, when a militia alliance overran Tripoli, forcing the government to take refuge in the east.

The United Nations is pressing the rival sides to accept a power-sharing deal.

On December 17, under UN guidance, lawmakers from both sides and a number of independent political figures signed a deal for a unity government, but the agreement has yet to be implemented.

It has so far failed to win unanimous backing from Libya's two rival parliaments, one based in the eastern city of Tobruk and the other in Tripoli.

In a statement after Thursday's attack, EU foreign policy chief Federica Mogherini urged Libyans to back the agreement.

"Once again the Libyans are mourning victims of an attack," she said. "The people of Libya deserve peace and security and... they have a great opportunity to set aside their divisions and work together, united, against the terrorist threat facing their country."

World powers fear Libya could descend further into chaos and become a stronghold of Daesh on Europe's doorstep.

The group claimed a string of atrocities in Libya last year, including the January attack on a luxury hotel in Tripoli known for hosting foreign diplomats and Libyan officials, which killed nine people.

A month later it released a video showing the beheading of 21 Coptic Christians, all but one of them Egyptians, that the terrorists said they captured in Libya in January.

In a report to the UN Security Council in November, International Criminal Court chief prosecutor Fatou Bensouda said that Daesh had been responsible for at least 27 car and suicide bombings in Libya in 2015.

Daesh has in recent days launched a series of attacks on oil facilities in eastern Libya, pushing east from the group's coastal stronghold of Sirte.

Officials have warned of crippling consequences for the country if the terrorists manage to seize control of Libya's oil resources.

Oil is Libya's main natural resource, and the country sits on reserves estimated at 48 billion barrels, the largest in Africa.

Calls have been growing for a possible foreign military intervention to bring stability to Libya and contain Daesh, which is reported to have at least 3,000 fighters in the country.

Terrorists have also used Libya as a springboard for attacks across the border in Tunisia, including at the capital's National Bardo Museum and a beach resort, killing a total of 60 people, all but one of them foreign tourists