The China subsidiary of U.S.-based ConocoPhillips on Friday extended an apology for conduct that led to two oil spills in north China's Bohai Bay, pledging to accelerate its clean-up efforts.

The company vowed to take measures to ensure that similar accidents will not happen in the future.

Crews try to recover oil-based mud from the seabed near the Penglai 19-3 C platform.

It said that it will submit a proposal to the State Oceanic Administration (SOA), China's central maritime authority, regarding its handling of the accident and will also inform the public about its clean-up efforts.

The company came under criticism from the SOA on Wednesday, with the administration stating that the measures taken by the company so far have only been temporary in nature and cannot effectively eliminate the risk of more spills.

The administration demanded an apology from ConocoPhillips and asked it to provide more detailed information to the public and the government.

The company previously reported spills coming from two of its platforms to authorities in June. It was told by the SOA to contain an oil spill originating from its "B" platform and recover oil-contaminated mud from its "C" platform, both of which are located in the bay's Penglai 19-3 oilfield, before September.

However, oil slicks found earlier this month near the platforms led to suspicions that the company has made little progress in checking for potential oil spill sources.

In regard to intermittent spills originating from a natural fault near the B platform, the company said it is working to stop the spills under the guidance of the SOA.

The cause of the intermittent spills originating from the "C" platform is still under investigation, the company said.

It said the amount of oil lost during the spills so far totals 115 cubic meters, or 700 barrels of oil.

The spills have spread to beaches in the nearby provinces of Hebei and Liaoning and have been blamed for losses in the provinces' tourism and aquatic farming industries.

The company said it will continue to work with the government and international experts to evaluate the accident's ecological implications.

Oil-drilling operations in the field are conducted by ConocoPhillips China in cooperation with the China National Offshore Oil Corporation (CNOOC), the country's largest offshore oil producer.