The country's top offshore oil and gas producer announced a plan Tuesday to cooperate with foreign companies to explore undersea reserves in 26 blocks off China's coastline, including 22 in the South China Sea.

The plan, which experts say does not cover areas with rival territorial claims this time, came after the company, China National Offshore Oil Corp (CNOOC), sent bidding invitations to foreign companies to explore nine blocks in the disputed waters of the South China Sea in June.

Foreign companies can file an application or inquiry with CNOOC for access to the offshore blocks' information before November 30, according to a statement on CNOOC's website. The 26 blocks tendered, mostly nearby China's Hainan and Guangdong provinces and covering a total 73,754 square kilometers, include one in the Bohai Bay, three in the East China Sea, and 22 in the eastern and western parts of the South China Sea.

"CNOOC's move shows its confidence and gradual progress in oil and gas exploration in the South China Sea," Han Xiaoping, chief information officer at Chinese energy portal china5e.com, told the Global Times. China is showing it is able to carry out independent oil and gas exploration at deep sea, he added.

The previous bids on the nine blocks cover 160,000 square kilometers with seven located in the Zhongjianan Basin and the other two in the Wan'an and Nanweixi basins. The bids were met with strong objections and triggered protests from Vietnam, which claimed they are illegal and encroached on its territorial waters. State-run Vietnam Oil & Gas Group had urged foreign companies not to join the bidding of nine lots invited by CNOOC, according to a Vietnam News Agency report on June 27.

China's foreign ministry defended the legitimacy of CNOOC's plan, saying in June that it was "normal business activity," and that it is in line with relevant Chinese laws and international practices.

The bidding for exploration in the nine blocks is going well and some US companies have expressed their intention to participate in the bidding for the nine blocks, said CNOOC's chairman Wang Yilin in July.

The company also signed two production-sharing contracts with Royal Dutch Shell PLC to explore two offshore oil blocks in the South China Sea's Yinggehai basin on July 25. Shell's media officer in China, Li Lusha, told the Global Times Tuesday the two blocks are close to Hainan Province and off the disputed area, but she did not reveal whether the company would have further cooperation with CNOOC.

"I don't think foreign companies would be subject to pressure or risks if they cooperate with CNOOC, as China has been firm on its territorial sovereignty, in which case the companies' interests could not possibly be compromised due to disputes," said Sun Xiaoying, a researcher on Southeast Asia with the Guangxi Academy of Social Sciences.