China's third-largest oil and gas producer CNOOC Ltd has voluntarily requested the Committee on Foreign Investment in the United States (CFIUS) to review its acquisition plan for Unocal Corp, in a bid to clear up doubts about the deal.

China National Offshore Oil Corporation's (CNOOC) oil rigs is seen in China's Liaodong Bay of the Bohai sea February 3, 2005. [newsphoto]

Beijing-based CNOOC Ltd said on Saturday that it had filed a notice with CFIUS for the committee to review its US$18.5 billion all-cash offer to buy the US oil conglomerate Unocal Corp, wrangling with a US$16 billion cash-plush-stock proposal from the California-based Chevron Corp.

"It's a voluntary notice from CNOOC Ltd. We hope the review will enter formal proceedings as soon as possible as we are sure that the transaction is purely commercial," said a CNOOC spokesman.

"We welcome this opportunity and believe that once all the facts are known and the commercial purpose and terms of the transaction are fully understood, many initial wrong impressions will be corrected, and many doubts and questions will be favourably resolved," said CNOOC Chief Financial Officer Yang Hua on Saturday.

CNOOC's all-cash bid, although more attractive financially than Chevron's offer, has triggered rising concern among US Government officials it could be subsidized by the Chinese Government and thus threaten America's national security.

"This filing gives CNOOC the opportunity to comply with all US rules and regulations in an open and transparent manner, and to discuss our proposal fully... We are co-operating fully and look forward to a formal review conducted in an expeditious manner," said Yang.

"CNOOC's proposed transaction has generated a significant amount of interest, and we look forward to beginning the CFIUS review to respond to that interest and provide timing certainty to Unocal stockholders for our superior offer," said Yang.