Libya’s UN-backed unity government said on Friday that four of its ministers had been sacked just three months after it set up office in the capital Tripoli.

Libya's UN-backed unity government said on Friday that four of its ministers had been sacked just three months after it set up office in the capital Tripoli.

Their departure is a new setback in efforts to unify the North African country which has a rival administration in the east.

"The dismissed ministers were absent from their work and refused to take up their duties in the Government of National Unity... for over 30 days," the GNA said in a statement on its website.

The justice, economy and industry, finance, and national reconciliation ministers -- all easterners -- were dismissed from their posts on Thursday, it added.

That is three months to the day since Prime Minister Fayez al-Sarraj, a businessman from Tripoli, sailed into the capital under naval escort.

The GNA, the result of UN-backed power-sharing agreement in December, took control of several ministries in April.

But it has yet to receive a vote of confidence from the country's elected parliament in the eastern city of Tobruk that would give it authority over the whole country.

In March, just over half the parliament's members signed a statement of support for the GNA, but a formal vote of confidence has been repeatedly delayed.

Sarraj named a cabinet of 18 ministers in February.

He gave several important portfolios to easterners -- including Colonel Al-Mahdi al-Barghathi, a popular military figure who is defense minister.

GNA-allied forces have been fighting the ISIL group in its stronghold of Sirte for the past seven weeks.

Libya's oil-dependent economy has also been hit hard by the sharp fall in world prices.