Turkish forces backing the UN-recognised government are under strain after strongman Khalifa Haftar called on his fighters to "drive them out, as talks drag on to end a long-running war in the oil-rich nation.

Turkish support for the Government of National Accord (GNA) in Tripoli helped stave off an April 2019 offensive by Haftar, who is backed by Russia, Egypt and United Arab Emirates.

The sides struck a ceasefire agreement in October, setting the stage for elections at the end of next year.

But Haftar said there would be "no peace in the presence of a coloniser on our land" during a speech on Thursday.

"We will therefore take up arms again to fashion our peace with our own hands... and, since Turkey rejects peace and opts for war, prepare to drive out the occupier by faith, will and weapons," Haftar said.

The Turkish parliament this week adopted a motion extending the deployment of soldiers in Libya by 18 months.