North Korea on Thursday test-fired four short-range missiles, South Korean military officials said, further fuelling tension sparked by its nuclear standoff with the international community.
The missiles -- apparently surface-to-ship ones -- were fired into the East Sea (Sea of Japan) between 5:20 pm (0820 GMT) and 9:20 pm, 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 (60 miles) 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 Korea's 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 the days after its atomic test -- the second since 2006 -- Pyongyang had fired a total of six short-range missiles and renounced the truce in force on the Korean peninsula.
In response to the UN resolution tightening curbs on its missile and atomic activities, it vowed to build more nuclear bombs.
US and South Korean officials believe ailing leader Kim Jong-Il, 67, is staging a show of strength to bolster his authority as he tries to put in place a succession plan involving his youngest son.
Japan's Prime Minister Taro Aso condemned Thursday's launches, telling reporters: "We have repeatedly warned that such a provocative act is not beneficial for North Korea's national interest."
In Beijing, a US delegation Thursday met officials for talks on giving the UN sanctions more teeth.
The support of China, the North's sole major ally and largest trade partner, is seen as crucial in making the sanctions stick.
The delegation, led by Philip Goldberg -- the State Department's point man on coordinating implementation of the sanctions -- met officials from the foreign ministry.
His team includes members of the National Security Council and the departments of Treasury and Defence.
Goldberg declined comment on China's 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."
US warships have since mid-June been tracking a North Korean ship suspected of carrying weapons. The Kang Nam 1 was reportedly headed for Myanmar but US officials said Tuesday it has now turned back.
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.
They are members of a forum which has tried since 2003 to persuade the North to scrap its nuclear programmes in return for energy aid and diplomatic and security benefits.
The North announced it was quitting the talks after the UN censured its long-range rocket launch on April 5.
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.
The South rejects the North's demand for huge pay rises and rent increases at Kaesong, and demands freedom for a South Korean worker who has been held for more than 90 days.
The North alleges the man slandered its political system and tried to incite a local woman worker to defect. It refuses to grant access to him.