BEIJING, August 24 (Reuters) - China's President Xi Jinping pledged to make concerted efforts with South Korea's President Moon Jae-in to address differences between the two countries properly, the official Xinhua news agency said on Thursday. Xi made the remarks in a congratulatory message sent to Moon on the 25th anniversary of the establishment of China-South Korea diplomatic relations, Xinhua said. Development of China-South Korea relations made a positive contribution to regional peace and development, Xinhua cited Xi as saying. The news agency did not provide further details. South Korea and the United States agreed to deploy the Terminal High-Altitude Area Defense (THAAD) anti-missile system in response to the growing missile threat from North Korea. However, the installation of the missile system has angered China, which says its powerful radar will be able to look deep into its territory and undermine regional security. China has pressed South Korean businesses through boycotts and bans, such as ending Chinese group tours to South Korea and closing most of South Korean conglomerate Lotte Group's Lotte Mart retail stores in China. Chinese Foreign Ministry spokeswoman Hua Chunying said the exchange congratulatory messages was consistent with usual practice. Many tangible and mutual benefits had been delivered to people of both countries since the establishment of diplomatic ties, she told a daily news briefing. "We hope the South Korean side can summarise and look back on the experiences and lessons from the 25 years of diplomatic relations and take constructive actions to appropriately address relevant sensitive issues and differences to improve relations between China and South Korea," Hua said. "On the issue of THAAD, China's position is very clear, resolute and there is no change." Moon has also pushed China, North Korea's most important ally and trading partner, to do more to rein in Pyongyang's missile and nuclear weapons programmes. North Korea has conducted two nuclear tests and dozens of missile tests since the beginning of last year, significantly raising tension on the heavily militarised Korean peninsula and in defiance of U.N. Security Council resolutions. Two intercontinental ballistic missile tests in July resulted in a new round of tougher global sanctions.