Libyan House of Representative
"The election for members of the House of Representatives will take place 30 days after the presidential vote," still scheduled for December 24, parliamentary spokesman Abdullah Bliheg told a press conference.
Elections are supposed to help unify the country after years of conflict and division, but disputes over their legal and constitutional basis have laid bare the extent of the split between the country's east and west.
The House of Representatives, based in the eastern city of Tobruk, has been in disagreement over electoral laws with a rival body, the equivalent of Libya's senate, in the western city of Tripoli.
Bliheg said holding the presidential poll was the priority, leading to the move to delay the legislative ballot.
"In recent years the country has not been able to stabilise itself through the parliamentary system," he said.
"It was necessary to organise the presidential elections as soon as possible."
Libya has endured a decade of conflict since the 2011 fall of dictator Moamer Kadhafi in a NATO-backed uprising, which unleashed a complex civil war that dragged in multiple foreign powers.
A landmark ceasefire between eastern and western camps last paved the way to a UN-backed peace process.
The Tripoli-based unity government of interim Prime Minister Abdulhamid Dbeibah took office in March with a mandate to lead the country to December elections.