SEOUL, July 11 (Reuters) - North Korea on Tuesday condemned U.S. President Joe Biden's decision to send cluster munitions to Ukraine as a "criminal act" and demanded an immediate withdrawal of the plan.

The fact that Biden had admitted it was a difficult decision showed he was aware of the disastrous consequences of the use of cluster munitions, North Korean Foreign Minister Choe Son Hui said in a statement carried by the official KCNA news agency.

"I, on behalf of the DPRK government, vehemently denounce the U.S. decision to offer WMD (weapons of mass destruction) to Ukraine as a dangerous criminal act to bring a new calamity to the world, and strongly demand the U.S. withdraw the decision immediately," she said.

DPRK refers to the North's official name, the Democratic People's Republic of Korea.

Reclusive North Korea has forged closer ties with the Kremlin and backed Moscow after it invaded Ukraine in February last year.

"The U.S. has made a very dangerous choice ... which brings to light once again its true colours as destroyer of peace regarding aggression and massacre as its national policy and mode of existence," Choe said.

The United States announced last week it would send Ukraine the weapons controversial for the danger they pose to civilians long after fighting ends as part of an $800 million security package.

Many U.S. allies and partners helping aid Ukraine are among the 111 state parties to the Convention on Cluster Munitions, which prohibits all use, stockpiling, production and transfer of cluster munitions and came into force in 2010.

North Korea is not a party to the convention. Russia, Ukraine and the United States have also not signed the convention

Ukraine said the U.S. decision would help to liberate Ukrainian territory but promised the munitions would not be used in Russia.