Dozens of Libyan lawmakers supporting the internationally recognised government in Tripoli on Sunday elected a "provisional speaker" as they vied with loyalists of commander Khalifa Haftar for control.
Libya has been mired in chaos since the 2011 ouster of Moamer Kadhafi, with Haftar backing a rival administration in the east that includes the country's parliament.
The military strongman's forces last month launched an offensive to capture the seat of the Government of National Accord in the capital.
Forty-two deputies have convened in Tripoli as part of a boycott of the parliament in the east to protest Haftar's assault on Tripoli.
Lawmaker Soleiman al-Faqih said the group had elected senior member Sadeq al-Keheli as speaker for a period of 45 days in the hope that other legislators would join their side.
Weeks of clashes around Tripoli between Haftar's forces and those supporting the unity government have left some 400 people dead and more than 1,900 wounded, the World Health Organisation says.