New Delhi, Sept. 16: The agreement between ONGC Videsh and PetroVietnam to explore oil and gas in offshore Vietnam could cast a shadow on India’s relation with China during Chinese President Xi Jinping’s visit, which begins tomorrow.

“OVL and PetroVietnam, the major oil producing state-owned company of Vietnam, have signed a letter of intent to participate in the exploration of oil and gas in offshore Vietnam,” the Indian exploration firm said in a statement here today.

However, an agency report from Beijing quoting a foreign ministry spokesperson said, “We hold no objection to legitimate and lawful agreement between Vietnam and a third country. But one thing is to be clear. If such an agreement concerns waters administered by China or if such a co-operation project is not approved by the Chinese government, we will be concerned about such an agreement and we will not support it.”

China has conveyed similar objections about previous wells allotted to ONGC by Hanoi. China virtually claims almost all of the South China Sea. Its claims of sovereignty are opposed by Vietnam, the Philippines, Malaysia and Brunei.

India had earlier told China that its objections to OVL’s explorations in South China Sea had “no legal basis” as the blocks belonged to Vietnam.

The south east Asian nation has cited sovereignty rights over the blocks according to the United Nations Convention on the Law of the Sea, 1982.

The overseas arm of state-run explorer Oil and Natural Gas Corp (ONGC) will consider exploring in two to three blocks out of the five areas in South China Sea that Vietnam had offered on a nomination basis in November last year.

The five blocks or areas — 17, 41, 43, 10&11-1 and 102&106/10 offered in November last year lie outside the territory claimed by Beijing in the South China Sea.