Chinese President Xi Jinping told his South Korean counterpart that China opposes the U.S. deployment of the THAAD anti-missile system in South Korea, Xinhua state news agency reported on Monday.
China has repeatedly expressed anger since the United States and South Korea made a final decision in July to deploy the U.S. Terminal High Altitude Area Defence (THAAD) system in the South to counter missile and nuclear threats from North Korea.
"Mishandling the issue is not conducive to strategic stability in the region and could intensify disputes," Xinhua quoted Xi as telling Park Geun-hye in the eastern Chinese city of Hangzhou.
Park, Xi and other leaders from the Group of 20 major economies are meeting in Hangzhou.
Beijing worries the system's radar will be able to track its military capabilities.
North Korea, which had threatened a "physical response" against the THAAD decision, has conducted a series of military technology tests this year, including a fourth nuclear test in January, in defiance of U.N. Security Council sanctions that were tightened in March.
It fired a submarine-launched missile on August 24 that flew about 500 km (300 miles) toward Japan, a show of improving technological capability for the isolated country.
"North Korea’s fourth nuclear test and ballistic missile provocations this year have gravely damaged peace on the Korean peninsula and the region and posed a challenge to the development of South Korea-China ties," Park told Xi, according to South Korea's Yonhap news agency.
Officials in South Korea and the U.S. have tried to assuage Chinese fears, insisting that the move is designed purely to counter growing missile threats from North Korea, and not to target China.
Xi said China and South Korea shared "broad common interests" and should "cherish their existing cooperative foundation and overcome difficulties and challenges", Xinhua reported. He also reaffirmed China's commitment to the denuclearization of the Korean peninsula.
Since the decision to deploy THAAD in South Korea, China's Defence Ministry has since confirmed that it is pressing ahead with its own anti-missile system tests.