BEIJING (AFP) - China's Defence Ministry Wednesday urged the United States to respect its security following a standoff near its south coast, state media reported, amid warnings from Beijing about future ties. Earlier in the day, China had also expressed anger over US criticism of Beijing's handling of Tibet and warned that such statements from Washington could harm bilateral military relations just as they seemed to be warming. "We urge the US to respect our legal interests and security concern," Ministry spokesman Huang Xueping was quoted as saying by the official Xinhua news agency in relation to Sunday's naval incident. Xinhua's report said China wanted to make sure the US did not again carry out "activities in China's special economic zone in the South China Sea" and that it had lodged "a solemn representation to the United States." The spat between Washington and Beijing, which has seen numerous claims and counter-claims in the past few days, began after the Pentagon said Chinese vessels had harassed a US Navy ship in international waters.The US protested to Chinese authorities in Beijing and to the defence attache in Washington over the incident, which occurred on Sunday in the South China Sea, about 120km south of Hainan Island. The Pentagon said Chinese boats moved directly in front of the USNS Impeccable, forcing the ship to take emergency action to avoid a collision, and then dropped pieces of wood into its path. Beijing hit back on Tuesday rejecting that account and demanding the US cease what it called illegal activities in the South China Sea. On Wednesday, Chinese Foreign Ministry spokesman Ma Zhaoxu said that "the US claims are gravely in contravention of the facts," according to Xinhua. The Xinhua report also quoted Huang as saying that the sea area where "the US ship conducted illegal activities" was China's exclusive economic zone, and the United States should abide by laws regarding it. "We demand that the US take effective measures to prevent similar acts from happening," Huang said. China also reacted angrily to a storm of international criticism over its rule of Tibet, telling the US to stop interfering and calling the Dalai Lama a whingeing child. "The US, ignoring the facts, has made unwarranted criticism of China on the issue of Tibet... We express our resolute opposition and strong dissatisfaction with this," Chinese Foreign Ministry spokesman Ma Zhaoxu said Wednesday in response. "We ask the US side... to acknowledge that Tibet is a part of China and oppose Tibetan independence, avoid harming overall China-US relations, and stop using the Tibet issue to interfere in China's internal affairs."