BEIJING (AFP) - China on Saturday denounced proposed US arms sales to Taiwan worth 6.5 billion dollars, according to state media, hours after Taiwanese President Ma Ying-jeou had thanked Washington. Chinese Foreign Ministry spokesman Liu Jianchao said the Chinese government and people firmly opposed the move, which seriously damaged China's interests and Sino-US relations, Xinhua news agency said. The Pentagon notified Congress Friday of 6.5 billion dollars in possible arms sales to Taiwan that would include advanced interceptor missiles, Apache attack helicopters and submarine-launched missiles. The Defence Security and Cooperation Agency said the proposed sales were aimed at improving Taiwan's defences and would not alter the basic military balance in the region. It would end a year-long lull in US arms sales to Taipei, which has enjoyed improved relations with China since President Ma was elected earlier this year on a platform of easing tensions with the mainland. "All foreign military sales are discussed and approved (based on) long established inter agency procedure, and we only recently finished that procedure with regard to these notifications for Taiwan," a State Department official said. Taiwanese President Ma on Saturday thanked Washington for the planned deal with the island, while reiterating his pledge to improve ties with rival China. "President Ma Ying-jeou would like to thank the US government. He is committed to upholding national sovereignty and security while promoting cross-strait peaceful developments," said presidential spokesman Wang Yu-chi. "This also shows that Taiwan and the US have entered an era of mutual trust and the discord in the past eight years is over," Wang said. The proposed sales would involve 330 Patriot Advanced Capability (PAC-3) missiles worth up to 3.1 billion dollars and 30 AH-64D Apache Longbow helicopters worth 2.5 billion dollars. Taiwan has asked to buy 31 UGM-84L submarine launched Harpoon anti-ship missiles valued at up to 200 million dollars. It also requested 182 Javelin guided missiles with 20 Javelin command launch units worth 47 million dollars. "The proposed sale will help improve the security of the recipient and assist in maintaining political stability, military balance and economic progress in the region," the DSCA said. Congress has 30 days to raise objections to the proposed sales, which are likely to face criticism from China. The announcements followed a visit to the United States this week by Taiwanese defence minister Chen Chao-min, the first of its kind since 2002. Taiwan and the mainland have been governed separately since they split in 1949 at the end of a civil war but Beijing sees the island as part of its territory awaiting reunification, by force if necessary. China has repeatedly threatened to invade Taiwan should the island declare formal independence.