Libya's rival politicians have signed a UN-brokered deal to form a unity government in a nation split by more than four years of conflict, BBC News reports.

UN envoy Martin Kobler described the deal as historic, saying Libya had "turned a page" in efforts to achieve reconciliation and stability.

However, the heads of the rival parliaments failed to sign the deal because of major disagreements.

Armed groups which control much of Libya were not part of the talks.

Libya has been in chaos since the 2011 overthrow of long-serving ruler Muammar Gaddafi by Nato-backed forces. It has two rival governments, one based in the main city, Tripoli, and the other about 1,000km (620 miles) away in the port city of Tobruk.