Benghazi - Libya's internationally recognised parliament on Monday voted no confidence in a UN-backed unity government, in a blow to efforts to end the country's political chaos.
But lawmakers gave prime minister-designate Fayez al-Sarraj a 10-day deadline to come up with a new unity government line-up, they said in a statement issued later.
The government of National Accord led by Sarraj is struggling to assert its authority in Libya, which has been riven by turmoil since the 2011 overthrow of dictator Muammar Gaddafi.
National support for the GNA is seen as crucial to restoring stability and to tackling the Libyan branch of the Islamic State group, which pro-GNA forces are battling in the jihadists' coastal stronghold of Sirte.
But at a session on Monday, the House of Representatives, Libya's recognised legislature based in the far east, refused to give its support to the GNA.
"The majority of lawmakers present at the parliament session voted no confidence in the government," said parliament spokesperson Adam Boussakhra.
Parliament speaker Aguila Saleh as well as 101 lawmakers attended Monday's vote, the assembly said on its website.
Sixty-one parliamentarians rejected the GNA, it said, 39 abstained from voting and a lone parliamentarian voted confidence in the government.
The unity government was the result of a UN-brokered power-sharing deal struck in December, but has struggled to unite the North African country and fully assert its authority.
A rival government in the east has refused to cede power until the House of Representatives passes a vote of confidence, which has been repeatedly delayed including over a lack of quorum.
Monday's vote was "the first time quorum has been reached in five months," Boussakhra said.
After one such vote postponement in February, 100 lawmakers in the 198-member legislature said they supported the GNA but had faced intimidation.
The parliament, in a statement approved by lawmakers who attended Monday's session, gave Sarraj a "last chance" to present a new line-up for a unity government within 10 days.
It called for "a consensus between members of the presidential council" of the GNA headed by Sarraj to select no more than eight to 12 candidates for the new cabinet.
Sarraj named a cabinet of 18 ministers in February, and four of them were dismissed last month because they never took office.
Mattia Toaldo, a Libya expert with the European Council on Foreign Relations, warned Monday's vote could lead to "a new institutional crisis" in the war-wracked country and called for "immediate international mediation".
"We will have to see if Sarraj and the members of the (House of Representatives) who support him will accept the legitimacy of the vote," he said.
The GNA last month moved into its official Tripoli offices, more than 100 days after starting to work from a naval base in the capital.
Vying for control
Since the prime minister-designate arrived in Tripoli on March 30, the GNA has won the loyalty of the central bank and national oil corporation - depositors of the country's wealth - as well as cities and armed groups in western Libya.
And Sarraj's government has managed to gather forces who since May 12 have been battling to kick IS out of Sirte east of the capital.
Pro-GNA fighters, backed by US air strikes, have recaptured more ground from jihadists holed up in the centre of Sirte in recent days.
The jihadists seized control of Sirte, Gaddafi's hometown, in June 2015, raising fears they would use the city as a springboard for attacks across the Mediterranean in Europe.
Libya descended into chaos after the 2011 revolution that toppled and killed Gaddafi, with rival authorities vying for control of the country.
The House of Representatives has been based in the eastern city of Tobruk since a militia alliance including Islamists seized the capital in mid-2014.
More than 2.4 million people in Libya are in need of humanitarian assistance, the UN said on Friday.