TRIPOLI (REUTERS) - A tanker that loaded oil from a rebel-held port in eastern Libya has been halted by government forces but it has not yet reached a port controlled by government forces, Prime Minister Ali Zeidan told Reuters on Monday.

Oil officials said earlier navy forces had seized the North Korea-flagged tanker outside the rebel-held Es Sider port to escort it to a government-controlled port in western Libya.

Giving the first details of the operation, Prime Minister Zeidan said the tanker was not yet in western Libya. "The ship is around 20 miles from Es Sider," he said in an interview.

"It stopped due to darkness and won't move tonight but is under complete control and secured. Tomorrow it will move." Authorities would unload the crude from the tanker once it reached a western port and then launch legal measures against the potential buyers.

Mr Zeidan also said Libya would end the blockade of all rebel ports in the east either through talks or by military force.

"What is confirmed it that all ports will be liberated from the occupiers with all means possible," he said. "We prefer talks but if talks fail then the state will act," he said.