BEIJING: China today made it clear that it will "not support" the India-Vietnam agreement to enable ONGC to explore two more oil wells if they fall within the waters of the disputed South China Sea administered by it.Asked for his reaction to the agreement signed during President Pranab Mukherjee 's current visit to Vietnam, Chinese foreign ministry spokesman Hong Lei said China has no objection to any "legitimate and lawful" agreement between Vietnam and a third country."We have noted President's (Mukherjee) visit to Vietnam. I would like to point out that China has indisputable sovereignty over Nansha islands and adjacent waters," he 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 agreement concerns waters administered by China or if such cooperation project is not approved by the Chinese government , then we will be concerned about such an agreement and we will not support it," he said.Hong separately clarified to Indian media later that this is China's stand about oil exploration agreements between Vietnam and any other country, not simply India.While articulating its stand, China wants to be cautious as President Xi Jinping is starting his maiden visit to India tomorrow which is expected to enhance cooperation between the two countries.The reference to Nansha islands is what Vietnam calls Paracel islands which are part of a major dispute between Beijing and Hanoi.It is not clear where the two oil wells will be located. China has conveyed similar objections about previous well allotted to ONGC by Hanoi.China virtually claims almost all of the South China Sea. Its claims of sovereignty are firmly opposed by Vietnam, the Philippines, Malaysia and Brunei.The dispute between Vietnam and China over oil exploration flared up last May when Hanoi fiercely resisted Beijing's attempts to deploy a major oil rig.It resulted in major anti-Chinese riots in Vietnam leading to the death of four Chinese.Over 100 Chinese were injured in the incident. Over 400 foreign factories mostly run by Chinese were burnt down.Subsequently China has recalled over 7,000 of its workers from Vietnam over fears for their safety.The Communist neighbours however warmed up to each other in recent weeks with the visit of a special envoy from Hanoi who held talks with top Chinese leaders.During Mukherjee's visit to Hanoi, India and Vietnam signed seven pacts including a Letter of Intent (LoI) between the ONGC Videsh Limited (OVL) and Vietnam Oil and Gas Group (PetroVietnam).The LoI is aimed at further consolidating cooperation between India and Vietnam in energy sector and pave the way for future collaboration between the two countries.China has been exerting its influence in these waters which is not taken well by Vietnam and other bordering countries like the Philippines. Beijing has also objected to India's exploration projects in the Vietnamese oil blocks.