China and Indonesia conducted joint naval exercises in waters off Jakarta, Beijing said on Sunday, as the two countries work to improve trust and cooperation amid tensions in the South China Sea . The drills, which took place on Saturday morning, were part of the PLA Navy’s annual training programme, the defence ministry said. China’s Liuzhou and Suqian guided-missile frigates joined Indonesia’s KRI Usman Harun frigate and KRI Halasan missile craft in the exercises, which included communication drills, search and rescue operations and formation manoeuvres, it said. Mei Guoqiang, who heads the PLA Navy Southern Command’s offshore training formation team, told PLA Daily that the exercises would “help improve coordination between the warships, deepen professional communication, enhance mutual trust and cooperation and jointly demonstrate practical actions to safeguard regional peace and stability”. The exercises came just a week after Beijing announced it was sending three rescue ships , including one with a manned submersible capable of descending to 10,000 metres (33,000 feet), to help recover the Indonesian submarine that sank late last month with the loss of all 53 crew members. It was the first time China had joined an international submarine recovery mission. Observers said the operation would provide the PLA with valuable experience, though China’s involvement was greeted with some suspicion in Indonesia and the West regarding its true intentions. While military officials from China and Indonesia have called for closer cooperation, the two countries have clashed over fishing rights near the Natuna Islands in the South China Sea. Although Jakarta is not involved in any territorial disputes in the waterway, it considers the waters off the Natunas to be part its exclusive economic zone, though Beijing claims it has historical rights to fish there. The PLA Navy began its annual training programme in April. The defence ministry said last week that the country’s first domestically developed aircraft carrier, the Shandong, and its support group had begun an exercise in the South China Sea, soon after the Liaoning carrier group completed its latest manoeuvres in the waters.