SEOUL, South Korea - North Korea fired two short-range missiles into its coastal waters, a move believed part of regular military drills, South Korean military officials said Friday, amid an international stalemate over the North's nuclear weapons.

An official at South Korea's Defence Ministry said the missiles, fired Thursday into the waters off the North's western coast, were believed to have a range of about 100 kilometres.

Another official at the South Korean joint chiefs of staff said the launches were likely "part of regular military drills.''

Both officials spoke on condition of anonymity due to the issue's sensitivity.

North Korea's arsenal includes a variety of missiles, some believed able to reach parts of the United States.

The latest missile launches were not expected to heighten regional tension, because they demonstrated no new threat from the North.

Washington called the launches as "not constructive.''

"The United States and our allies believe that North Korea should refrain from testing missiles,'' said U.S. National Security Council spokesman Gordon Johndroe, accompanying President George W. Bush to the G8 summit in Germany.

Johndroe said the North "should focus on the denuclearization of the Korean peninsula and fulfil its obligations'' under a February agreement to shut down its sole nuclear reactor.

South Korea's Chosun Ilbo newspaper reported Friday the missiles were land-to-ship models and were launched from Chungsan on the North's western coast. The report cited unidentified individuals.

The JoongAng Ilbo newspaper said North Korea had issued a warning banning ships from its western waters since Tuesday. It cited unidentified military officials.

North Korea carried out an underground nuclear test explosion Oct. 9 but experts do not believe it has a bomb design advanced enough to be placed atop a missile.

The missiles launched Thursday were the second barrage fired by the North in two weeks.

Last month, it fired at least one short-range missile into waters of its eastern coast, which South Korean and U.S. official played down as part of routine military drills.

Thursday's launch comes amid the latest deadlock in nuclear talks with the North, which missed a mid-April deadline to shut down its nuclear reactor under an agreement with the United States and other powers.

North Korea has refused to act until it receives US$25 million in funds that were frozen in a Macau's Banco Delta Asia.

The money has been freed for release but the North has yet to withdraw it. It is apparently waiting for an electronic transfer to ensure the funds are clean.

South Korean Foreign Minister Song Min-soon said Seoul and its partners in the six-country nuclear talks -- which involve the two Koreas, the United States, China, Russia and Japan -- were exploring solutions to resolve the financial dispute.