BEIJING (AFP) - China on Tuesday warned US President Barack Obama not to meet the Dalai Lama and threatened diplomatic reprisals over US arms sales to Taiwan, widening an escalating feud between the worlds top powers. Beijings tough rhetoric piled pressure on a crucial relationship already severely strained over Googles threat to halt operations in China, which sparked a row over Internet freedom, and a host of trade and currency disputes. China and the US are working together on several pressing international disputes, including fraught negotiations aiming to curb the nuclear ambitions of North Korea and Iran. But Beijing hinted Tuesday that it may no longer be willing to play by US rules on such key foreign policy issues, and blamed Washington for any negative consequences. China-US relations, in important international and regional issues, will inevitably be influenced (by the Taiwan deal) and the responsibility completely lies with the US, Foreign Ministry spokesman Ma Zhaoxu said. Ma also called on US companies selling arms to Taiwan - corporate giants like Boeing, Lockheed Martin and Raytheon - to back away from the arms deal, after earlier warning that Beijing could impose sanctions. US Deputy Under-Secretary of the Air Force Bruce Lemkin offered Washingtons first reaction, calling the Chinese broadside unfortunate. This is a policy decision based on principle, and based on our commitment in the Taiwan Relations Act, he told reporters on the sidelines of the Singapore Airshow. US President Barack Obama still plans to meet the Dalai Lama, the White House said on Tuesday, despite China warning that such a meeting would hurt ties between the worlds biggest and third-biggest economies. The President told Chinas leaders during his trip last year that he would meet with the Dalai Lama and he intends to do so, White House spokesman Bill Burton told reporters traveling on Air Force One to New Hampshire, where Obama was due to speak at a town hall-style meeting. On Tibet, Beijing reiterated its long-standing opposition to any meeting between Obama and the Dalai Lama, who is due to visit Washington later this month on a trip to the US but no meeting with the US President has been announced. Such a meeting would seriously undermine the political foundation of Sino-US relations, Zhu Weiqun, Executive Vice-Minister of the Communist Party body that handles contact with the Dalai Lama, told a news conference. If the US leader chooses to meet with the Dalai Lama at this time, it will certainly threaten trust and cooperation between China and the United States, Zhu said. We oppose any attempt by foreign forces to interfere in Chinas internal affairs using the Dalai Lama as an excuse, he added. On Iran, Chinese Foreign Ministry spokesman Ma Zhaoxu said there was still room for negotiations to resolve the standoff over Irans disputed nuclear programme, after Washington urged Beijing to support sanctions on Tehran. There is still room for diplomatic efforts, he said. China always believes that dialogue and negotiations are the best way to resolve this issue, he said, after warning that Beijings cooperation with Washington on international issues could suffer over US arms sales to Taiwan.