Four Chinese vessels sailed into territorial waters around disputed islands in the East China Sea, Japan said today, as Tokyo attempts to engage with Beijing to press North Korea over its latest nuclear test. The four coastguard vessels sailed into waters surrounding the islands, administered as Senkaku by Japan and claimed as Diaoyu by China, at around 10:30 am (local time) and left about 90 minutes later, the Japan Coast Guard said. The two countries are locked in a long-running dispute over the uninhabited islets. China regards them as its own, rejecting the view it violates Japan's territorial waters. The latest incident comes at a tense time for the region after Pyongyang conducted its fifth and most powerful nuclear test Friday, to the outrage of its neighbours and the international community. Japan, the United States and South Korea have asked China - one of North Korea's few allies - to use its leverage to persuade Pyongyang to comply with UN sanction resolutions. Japan has routinely complained that China is escalating regional tensions by regularly sending ships to the island chain despite repeated protests from Tokyo. Today was the first time the Chinese ships had sailed into the waters around the tiny islands since Japanese Prime Minister Shinzo Abe met Chinese President Xi Jinping last week at the G20 Summit in Hangzhou, China. At the meet Xi and Abe sought to improve ties, with Xi saying the two should "put aside disruptions". However the rapprochement only went so far, with the Chinese leader also urging Japan to "exercise caution" on territorial disputes. Just weeks before the summit, hundreds of Chinese fishing boats, accompanied by government ships, had flooded into nearby waters, infuriating Tokyo. Japan is boosting defence ties with the Philippines and other Southeast Asian nations, some of which have their own disputes with Beijing in the South China Sea.