Libyan parliament on Monday voted against the UN-backed unity government, with 66 votes to reject it, 12 abstained from voting and one voted for approval.
Quorum was formed for a voting session for the first time since January in the eastern Tobruk-based parliament, Xinhua news agency quoted a parliament official as saying.
The Tripoli-based Government of National Accord (GNA) was appointed based on an UN-sponsored peace deal signed by the country's political rivals in order to end the state of political division.
GNA, however, faced opposition from several members of the parliament.
Monday's voting was considered to be another obstacle to the government that has been trying to get the approval of the parliament.
Meanwhile, GNA's forces fighting the Islamic State Terrorist Group in Sirte were gaining more control of the city in a fight which started in May and has claimed the lives of at least 350 government fighters and has injured 1,000 others.