A general view shows the damage at the scene of an explosion at the Police Training Centre in the town of Zliten, Libya, January 7, 2016.

The U.N. Security Council on Friday strongly condemned the “heinous” suicide bombing claimed by ISIS militants that killed dozens in Libya and called on rival groups to speed up the formation of a unity government.

More than 50 people were killed in the attack on Thursday on a police training school in the coastal city of Zliten, a security source said, in the deadliest single attack in Libya since the fall of Muammar Qaddafi.

The 15-member council described the suicide bombing as a “heinous act” and said those responsible should be brought to justice.

It also condemned a separate attack the same day on a checkpoint in Ras Lanouf, home to a key oil terminal, in which six people died including a baby.

The council “urged all parties in Libya to join efforts to combat the threat posed by transnational terrorist groups exploiting Libya for their own agenda by urgently implementing the Libyan political agreement” setting up the unity government, said a statement.

The U.N. brokered the unity government deal that was signed by politicians last month, but the agreement does not have the full backing of Libya’s rival parliaments.

Libya has had rival administrations since August 2014, when an Islamist-backed militia alliance overran Tripoli, forcing the government to take refuge in the east.

EU foreign affairs Chief Federica Mogherini on Friday met in Tunis with the prime minister-designate of the new unity government, Fayez al-Sarraj, and unveiled a 100-million-euro aid package.

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