NEW YORK -- President Obama's special envoy on North Korea says the U.S. has no intention to invade the communist country or change its regime by force.

Stephen Bosworth told the Korea Society Tuesday night that this has been repeatedly made clear to North Korea. The envoy says North Korea's claim to be responding to a threat or hostile policy by the U.S. is "simply groundless."

Bosworth says "negotiations and dialogue are the best means to achieve the goal of complete and verifiable denuclearization of the Korean Peninsula."

North Korea said Tuesday it would use nuclear weapons in a "merciless offensive" if provoked -- its latest rhetoric apparently aimed at deterring any international punishment for its recent atomic test blast.

South Korea has informed the U.S. of up to 20 North Korean bank accounts suspected of being involved in counterfeiting, money laundering and other illegal transactions, a news report said Wednesday.

The move came as Washington considered punishing the North with its own financial sanctions apart from proposed U.N. sanctions. Seven key nations neared agreement on a new U.N. resolution that would toughen sanctions against North Korea for defying the Security Council and conducting a second nuclear test.

South Korea gave the U.S. the information on some 10 to 20 North Korean bank accounts in China and Switzerland at Washington's request, South Korea's Chosun Ilbo newspaper reported, citing an unidentified government official.

Separately, South Korea's Finance Ministry has imposed sanctions on three North Korean companies for helping the country's April 5 long-range rocket test. The move was largely symbolic because the firms don't do business with South Korea.

The North has long been accused of being involved in the counterfeiting of US$100 bills and money laundering -- accusations Pyongyang has denied.

In 2005, the U.S. imposed financial restrictions Banco Delta Asia, a bank in the Chinese territory of Macau, over allegations of money laundering and other financial crimes involving North Korea. The move effectively cut the North off from the global financial system.

South Korea's chief nuclear envoy Wi Sung-lac said Tuesday that the Security Council is expected to adopt a resolution on North Korea within a couple of days, the South's Yonhap news agency reported.

Wi arrived late Tuesday in Beijing for talks with top Chinese officials on the North's nuclear stance, noting China's "special relationship" with Pyongyang.