A possible long-range missile launch by North Korea has Chinese authorities "very concerned", international media reported Thursday. Both China and Russia, the communist state's two last major allies, have expressed their alarm at the announcement by Pyongyang. The US and Japan have already warned of unspecified retaliation if the launch goes ahead. China is "very concerned about the current situation," the Foreign Ministry said in Beijing. Tensions have grown in recent weeks after US officials reported activity at a launch site near the country's northeastern coast, where the North Koreans could possibly be fuelling a Taepodong-2 missile. North Korea also said this week it has the right to launch a satellite, as it claimed to have done after a missile launch in 1998.