Rebel militias encamped in Libya's major eastern oil ports have refused to deal with the country's new Prime Minister Ahmed Maiteeq, in a blow to efforts to get Libyan oil flowing again.

Maiteeq's predecessor had reached a deal with the rebels that would have seen the ports of Hariga, Zuetina, Ras Lanuf and Es Sider handed back to the government. So far, only the two smallest ports, Hariga and Zuetina, have been opened.

While the sides had previously reached an agreement to sit down for talks about the larger ports, the rebels' statement on Wednesday seemed to snuff out any hope that a meeting could take place.

"We refuse to deal with Ahmed Maiteeq... Maiteeq came to power illegally," rebel spokesman Ali Hasi said.

The new Libyan PM took up his position on Sunday amid bitter protestations from opponents.

Libya has struggled to escape the chaos that followed the uprising that ousted former leader Muammar Gaddafi.

Vast amounts of weaponry remain in the country and are used by rebellious militias to control certain regions.

The central government lacks the authority and resources to control key transport hubs, including airports and seaports.

The groups in charge of the seaports have demanded an increased share of revenues from the government, as well as greater regional autonomy.

The oil blockades have reduced oil output from 1.4m barrels per day last summer, to just 250,000 barrels per day.