NORTH KOREA test-fired three short-range missiles Thursday, South Korea's Defense Ministry said, a move that aggravates already high tensions following Pyongyang's recent nuclear test and U.N. sanctions imposed as punishment.

Pyongyang first launched what officials described as two anti-ship missiles, followed by a third short-range device.

"This afternoon at 5:20 and 6 p.m. two short-range missiles were fired from Sinsang-ri," an official from the South Korean Defense Ministry said in an interview. The third missile was launched at 7:50 p.m., but officials could not confirm that it was fired from the same site.

North Korea had earlier called for a no-sail zone in waters off its east coast through July 10 for military drills. That designation was viewed as a prelude to such missile tests.

The launches came as North Korea's relations with the United States, South Korea and other countries were already severely strained after its May 25 underground nuclear test and a series of missile firings. The U.N. Security Council adopted a tough sanctions resolution last month to punish the communist regime.

"We had expected that they will fire short-range missiles at any time," South Korea's Foreign Minister Yu Myung-hwan said at a reception held at the U.S. ambassador's residence to mark U.S. Independence Day on July 4. "It's not a good sign because they are demonstrating their military power."

Philip Goldberg, a former ambassador who is in charge of coordinating the implementation of sanctions against the DPRK, was now in Beijing, Chinese Foreign Ministry spokesman Qin Gang said Thursday.

Separately, China's top nuclear envoy, Wu Dawei, left Thursday for Russia as part of diplomatic efforts to push North Korea back to the stalled nuclear disarmament talks, the ministry said.

The trip will take Wu to the U.S., Japan, and South Korea, the ministry said. The five nations have engaged in the talks since 2003 in an effort to persuade the North abandon its nuclear programs in return for economic aid and other concessions.

Earlier in the day, Seoul's JoongAng Ilbo newspaper reported that North Korea could fire a barrage of missiles in coming days, including ballistic Scud or Rodong rockets that the North is banned from testing under U.N. resolutions.

North Korea has also threatened to test-fire an intercontinental ballistic missile. Last month, a Japanese newspaper reported that the North could test-fire a long-range missile toward Hawaii as early as July 4. The U.S. has increased defenses around Hawaii.

But Seoul's YTN television news network said Thursday that there are no signs of an imminent long-range missile launch.

(SD-Agencies)