India and Vietnam should be given a "strong response" if they insist on exploring oil and gas in waters claimed by China, a Chinese newspaper has said.

"China must first insist on exerting political pressure over both India and Vietnam, warning them that their joint exploration in the South China Sea are illegal and violate China's sovereignty," the Global Times said.

"If they conduct oil and gas exploration in waters under China's sovereignty, China should give a strong response," added the paper, which is known reflect hardline nationalist thinking in China.

The Times said Tuesday that its reporter wrote the story based on an interview with Su Hao, director of the Asia-Pacific Research Centre at the China Foreign Affairs University.

India's state-run Oil and Natural Gas Corp (ONGC) recently announced that it has accepted Vietnam's proposal to continue to explore for oil and gas in the South China Sea, it noted.

This happened after Hanoi offered additional data that could help make future exploration economically viable.

"Such a move is obviously a complete about-turn in India's policy as Indian officials had said in May that the ONGC had decided to return Block 128 to Vietnam since exploration there wasn't commercially feasible.

"Vietnam's renewed offer to India came after the China National Offshore Oil Corp (CNOOC) decided to offer nine blocks in South China Sea for joint exploration with foreign companies, including Block 128."

The Times said the "strategic intention" of India's renewed involvement in the South China Sea issue was obvious.

"New Delhi wants to further complicate the issue and seeks to pin down China in the area so it could gain dominance in affairs across the region.

"It is clear that such cooperation between Indian and Vietnamese companies in South China Sea is motivated more by politics than economic interests.

"India believes that the rise of China poses a challenge, and it is trying to find ways to contain China.

"To achieve the goal, India has conducted joint military drills and stepped up security cooperation with countries that have disputes with China in the South China Sea.

"At the same time, India also wants to strengthen its economic presence in the area.

"Vietnam's offer of joint oil and gas exploration in the South China Sea provides an excellent opportunity for India to promote its strategy.

"Vietnam wants to take advantage of India's strategy to confront China. New Delhi and Hanoi do share common interests on the issue," the newspaper said.

The Times said that compared to India and Vietnam, China had advantages in its deep water drilling technologies.

"When the conditions are ripe, China should expand its exploration of oil and gas in the South China Sea."