Libya's Tripoli-based government on Sunday called for an armed "mobilisation" against the Islamic State group after the jihadists claimed a suicide bombing that killed five fighters allied to the government.
A statement by the Tripoli government, which is not recognised by the international community, urged "officers, soldiers... and all security forces and revolutionaries to mobilise" against IS.
It also urged the international community to help it fight the "takfiri" (Sunni radical) jihadist group, saying it posed a "big threat" to Libya's security.
"The Tripoli government is determined to continue fighting extremism and criminal gangs who operate under what is known as the Islamic State until they are uprooted," the statement added.
It came hours after IS claimed a suicide bomb attack against the militia alliance Fajr Libya (Libya Dawn) that installed the Tripoli government, killing five of its fighters.
The dawn blast in northwest Libya is the latest in a series of attacks by IS in the politically divided North African country, where the jihadists have exploited chaos to gain a growing foothold.
"A car suicide bomber blew himself up near a checkpoint at an entrance of Dafniya," between the town of Zliten and Libya's third city Misrata, said a spokesman for Fajr Libya (Libya Dawn).
The attack killed five fighters and wounded seven others, he added.
IS claimed responsibility for the attack in a message posted on Twitter, identifying the suicide bomber as a Tunisian named Abu Wahib al-Tunsi.
The jihadist group also warned Fajr Libya to be ready for "war".
"The apostates of Fajr Libya... must know that a war is coming to cleanse the land of their filth unless they repent and go back to their true religion," said the extremist group.
Libya plunged into chaos after the 2011 NATO-backed uprising that toppled and killed long-time dictator Moamer Kadhafi, with battle-hardened former rebels armed with heavy weapons carving out their own fiefdoms.
Fajr Libya seized power in Tripoli last year, installing a new government and parliament in the capital opposed to the administration recognised by the international community and elected legislature.