SEOUL (Reuters/AFP) - North Korea test-fired four short-range missiles on Thursday, further stoking tension in the region that was already high due to Pyongyangs nuclear test and threats to boost its nuclear arsenal in response to UN sanctions. The missiles apparently surface-to-ship ones were fired into the East Sea (Sea of Japan) between 5:20pm (0820 GMT) and 9:20pm, defence ministry officials were quoted saying by Yonhap news agency. All were fired from a base at Sinsang-ri, near the eastern coastal city of Wonsan, a spokesman was quoted as saying. Other officials told the agency on condition of anonymity they landed about 100 kilometres off the coast, where the North has imposed a maritime ban until July 11 for what it calls a military drill. Spokesmen from the defence ministry confirmed the first three firings to AFP but could not be reached for comment on the fourth. It was the first military action which the hardline communist state had taken since the United Nations on June 12 imposed tougher sanctions for its May 25 nuclear test. South Koreas JoongAng Ilbo newspaper, quoting an intelligence source, said the North in the coming days is likely to fire a series of short-range missiles. Apart from ground-to-ship weapons, it said these would likely include Scud-B missiles with a range of 340 km. The North may also fire Rodongs, whose 1,300-km range would likely be shortened to some 400 km for the current round of testing, the paper predicted. In response to the UN resolution tightening curbs on its missile and atomic activities, it vowed to build more nuclear bombs. Japans Prime Minister Taro Aso on Thursday called North Koreas latest firings of short-range missiles a provocative act, the Jiji news agency reported. We have repeatedly warned that such a provocative act is not beneficial for North Koreas national interest, he told reporters at his residence. He added that we cannot understand why it continues provocative acts in various forms. Earlier Thursday the top government spokesman, Takeo Kawamura, had said that the Japanese government cannot rule out a North Korean missile launch soon, possibly on Saturday, the US Independence Day. In Beijing, a US delegation Thursday met officials for talks on giving the UN sanctions more teeth. The delegation, led by Philip Goldberg the State Departments point man on coordinating implementation of the sanctions met officials from the foreign ministry. China said on Thursday it was sending its envoy to the six-party talks to South Korea, Japan, Russia and the United States. North Korea, the sixth party, was not on the itinerary. China has consistently advocated dialogue and consultation, and achieving denuclearisation of the Korean peninsula through the six-party talks process, Foreign Ministry spokesman Qin Gang told a news briefing. Goldberg declined comment on Chinas position. The US position is that we want all the various aspects of the resolutions to work, he told reporters. It is our intention to fully implement the resolutions. China said its top envoy on the North Korean nuclear issue, Wu Dawei, had begun a visit to Russia, the United States, Japan and South Korea. North and South Korea meanwhile held more talks about the fate of their last major joint business project, the Seoul-funded Kaesong industrial estate just north of the border. But they failed to narrow differences or set the date for their next meeting, Seoul officials said. Analysts say they would likely panic only if there was military conflict on a peninsula, where 2 million troops face each other across one of the worlds most heavily armed borders. South Korean Foreign Minister Yu Myung-hwan said he was seeking a meeting of the foreign ministers of the six countries, including the North, on the sidelines of a regional security forum on July 23 in Thailand. Officials said the Norths military grandstanding is likely related to moves by its leadership to begin readying leader Kim Jong-ils youngest son as a future heir by consolidating the 67-year-old leaders power base.