The Libyan parliament has approved a no confidence motion in the country's UN-backed government.
The development is a major blow to international efforts to resolve the crisis in the deeply divided North African country.
Parliament spokesman Abdullah Ablahig said 101 politicians were present on Monday, enough to reach quorum for the vote. He said 61 supported it, 39 abstained and one member voted to support the government.
It is unclear what happens next. Some politicians claim the vote should automatically dissolve the government set up under a UN deal, while its supporters dispute such a move.
Libya's parliament is seated in the eastern city of Tobruk, while the government is based in the capital Tripoli.
Libya has been mired in conflict since the 2011 downfall of dictator Muammar Gaddafi.
MP Abdel-Salam Nassiya said the cabinet would now have to be changed to include more representation from Libya's east.
Galal Saleh, a pro-government politician, said those who support the government had been tricked because the parliament had not announced the confidence vote on Monday's agenda.
"This is cheating," he said, adding that the pro-government bloc was invited to meet with opponents for a consultation, not a vote.