"There is no reason to believe that at some time in the future, when it serves their purposes, that they won't test another one. So I suspect some day they will," U.S. Army Gen. B.B. Bell, commander of U.S. Forces Korea, said at a news conference in Seoul.

Bell said the North - which conducted its first nuclear test on October 9 - is capable of testing another such device but he didn't elaborate on recent media reports that the North was preparing to do so.

Concerns about North Korea heightened abruptly last week in Asia after U.S. broadcaster ABC News reported Pyongyang might be preparing for another test. Citing unnamed U.S. defense officials, the network said the moves were similar to steps taken before the October blast.

Top U.S. and South Korean officials dismissed the speculation, saying there was no indication such a development was imminent.

In 2005, North Korea agreed to dismantle its nuclear program in exchange for security guarantees and aid but no progress has since been made in implementing the accord.

The United States held talks with North Korea in December to try to work out initial steps toward implementation of the breakthrough deal but they failed to produce any progress.

The talks - which also involve South Korea, China, Russia and Japan - ended in a deadlock over the U.S. financial restrictions imposed on the North over its alleged counterfeiting of US$100 bills and money laundering.

The U.S. and the North have provisionally agreed to hold the next talks on the financial dispute in the week starting January 22, according to South Korea's foreign minister, Song Min-soon. The previous talks - held on the sidelines of the main nuclear talks in Beijing - ended without any breakthrough.

Bell reaffirmed that South Korea-U.S. alliance remains strong to deter any possible aggression from the North.

About 29,500 U.S. troops are stationed in South Korea as a deterrent against a North Korean invasion, a legacy of the Korean War. The conflict ended in a cease-fire, not a peace treaty, leaving the two Koreas technically still at war.

The North says it needs nuclear weapons for protection from a U.S. attack.