One of Libya's rival governments has resigned, a step that bolsters efforts by a new, U.N.-brokered unity government to establish itself in the capitol, Tripoli, despite opposition from some local militias.

In a statement late Tuesday, the Tripoli-based government said it would "cease duties" as executive authority, and therefore absolve itself of responsibility for the country's fate.

The head of the new government, Fayez Serraj, arrived in Tripoli by sea last week to set up a temporary seat of power in a naval base despite threats from competing factions, which prevented him from arriving by air.

Western nations view the unity government as the best hope for ending Libya's chaos and uniting all factions against an increasingly powerful Islamic State affiliate. Another, Tobruk-based government still opposes the U.N.-backed body.