China National Offshore Oil Corp (CNOOC), the nation's third largest oil and gas producer, is in talks with Nigeria to acquire large stakes in some of the world's richest oil blocks, the Financial Times reported.

CNOOC, the nation's largest offshore crude producer, is bidding for 6 billion barrels of oil, equivalent to one in six barrels of proven reserves in Nigeria, the second largest oil producer in Africa.

CNOOC's potential bid came after Nigeria's oil licenses were set for renewal. Global oil giants including Shell, Chevron, Total and Exxon Mobil control or partially control 23 oil blocks in Nigeria, among which 16 licenses are set to expire.

The overall value of the Chinese offer has not been disclosed, although some details suggest a figure of about $30 billion, the FT said.

Yang Hua, president of CNOOC Ltd, the listed arm for the firm's overseas investments, declined to comment. CNOOC's spokesman Xiao Zongwei said he had never heard of the development.

Nigeria is also in talks with other "stakeholders" and no decision had been made on the licenses, the newspaper quoted a spokesman of the Nigerian president as saying.

Tanimu Yakubu, the Nigerian president's economic advisor, said China might not secure "anything close" to 6 billion barrels from the negotiations, adding, "We want to retain our traditional friends".

He, however, noted that the Chinese "are really offering multiples of what existing producers are pledging (for licenses). We love to see this kind of competition."

The largest investment CNOOC has made by far in Nigeria was a $2.69-billion stake purchased in 2006 in deep sea oil block OML-130.