The equipment hitch that caused an oil spill off China's northern coast on Tuesday was mostly cleaned up, according to China's largest offshore oil producer.

The oil spill has been dealt with efficiently and will be totally cleaned up on Tuesday, according to China National Offshore Oil Corporation (CNOOC).

This is the third time in less than two months for the oil giant to get involved in such an incident on the Bohai Sea.

The new leak occurred in CNOOC's Suizhong 36-1 oilfield at about 1:30 a.m. when the centralized control system of the oilfield's central platform broke down, the State Oceanic Administration (SOA) said in a press release.

It is estimated that about 0.1 to 0.15 cubic meters of oil was leaked, polluting an area of one square km, the press release said.

CNOOC used oil absorbent mats and sprayed oil dispersant to clean up the sea, it said.

SOA also dispatched a helicopter and used satellite remote sensing to monitor the development of the spill, it added.