Libya's ruling congress on Wednesday said it threatened to dismiss the new prime minister if he fails to name his new Cabinet by 8 October.
A spokesperson for the congress told reporters the ultimatum was given after Prime Minister-elect Mustafa Abushagur asked to extend the period in which he can form a government by 10 days.
Abushagur, elected by the congress on 12 September, was due to present his government list to the national assembly for approval by 28 September.
"If he fails to submit his proposed Cabinet by the deadline, we would consider his position as resigned, and there will be a vote for a new prime minister," spokesman Omar Homaidan told reporters.
In an emailed statement to Reuters, Abushagur's office said he would meet the deadline, adding he was working on forming a "coalition government."
"He will present his government before the end of the period identified on 8 October," the statement said.
"He would like to form a national coalition government in what is still a critical stage of Libyan history … There is a committee studying all the candidate applications for the government since a week ago."
Abushagur told Reuters this month his government would have a "geographical balance" in a country where regional rivalries are still rife.
He said improving security would be a priority after a deadly attack on the US Consulate in Benghazi, in which the US ambassador and three other Americans died.
The interim administration, in which Abushagur was deputy prime minister, has struggled to impose its authority on a myriad of armed groups who have refused to lay down their weapons.
