Libya's oil installations are undamaged and a cut in the country's oil output was caused by the departure of oil workers, the chairman of Libya's National Oil Corporation said on Tuesday.

Shokri Ghanem, who spoke to Reuters by telephone from his office in Tripoli, also said NOC was still overseeing Libya's oil production and exports.

NOC is still coordinating the production and exports, all the Libyan oil installations are safe. Oil wells and oil fields are not damaged, he said.

He said oil output had fallen by almost half because workers had left.

Almost half of the production went down. Some fields are still producing at capacity. Some are closed. It depends on the labour.

If they come back it is well protected and production can continue as before.