South Korea was assessing on Monday whether communist North Korea was preparing to withdraw from the international treaty that seeks to halt the spread of nuclear weapons.

A statement released by North Korea suggested it would pull out of the Treaty on the Nonproliferation of Nuclear Weapons — a move that would escalate the crisis over the isolated nation's decision to restart its nuclear facilities and expel International Atomic Energy Agency inspectors.

"We're closely watching what North Korea's next step would be," said a South Korean Foreign Ministry official, speaking on condition of anonymity at a briefing for reporters. "It could be a withdrawal from the nonproliferation treaty."

The treaty, which was adopted in 1968 and ratified by 187 countries, seeks to confine nuclear weapons to the United States, Russia, Britain, France and China.

At least three countries known to possess nuclear weapons — India, Pakistan and Israel — are not members of the treaty.

North Korea signed the treaty in 1985, but U.S. authorities believe the communist nation has at least one or two bombs made from 1980s-vintage plutonium.

In 1993, the North said it would withdraw from the treaty during a crisis over its suspected development of nuclear weapons. The crisis was resolved a year later with the Pyongyang regime agreeing to halt its nuclear weapons development in exchange for aid from the United States and other nations.

North Korea said in a statement Sunday that the United States violated the 1994 deal by halting promised energy supplies.

In the statement, North Korea said that the United States was "gripped by the Cold War way of thinking" and should agree to "face to face" dialogue to settle their nuclear dispute peacefully.

Many fear that if North Korea withdraws from the treaty, it would begin actively producing nuclear weapons and pose a direct threat to its neighbors in the region.

North Korea's nuclear moves have produced a flurry of diplomatic activity.

On Sunday, Secretary of State Colin Powell said the United States was "looking for ways to communicate with the North Koreans" to ease the nuclear crisis, but will do nothing to help Pyongyang unless it changes its behavior.

Japanese lawmakers, meanwhile, are reportedly weighing new sanctions against impoverished North Korea, hoping to pressure the regime. Japan is already withholding rice shipments.

Outgoing South Korean President Kim Dae-jung, who leaves office in February, said Monday that he would continue his "sunshine" policy of engaging North Korea to try to resolve the dispute peacefully.

The North's isolated communist government has been moving to reactivate operations at its main nuclear complex at Yongbyon that experts say could produce weapons within months.

In the past week, Pyongyang had removed U.N. seals and surveillance cameras from its nuclear facilities that were frozen under the 1994 accord.

On Friday, North Korea ratcheted up tensions by ordering the expulsion of two U.N. monitors — depriving the Vienna-based U.N. International Atomic Energy Agency of its last means of monitoring the North's plutonium-based nuclear weapons program.

U.S. officials said Sunday that Washington would enlist its Asian allies and the United Nations to intensify economic pressure on Pyongyang unless it abandons nuclear development.