North Korea has denounced the United States, Japan and other nations for their joint pledge to create a new mechanism to monitor sanctions on the North.

North Korean Ambassador to the United Nations Kim Song made the criticism on Sunday through the state-run Korean Central News Agency.

An expert panel of the UN Security Council monitored the implementation of sanctions on North Korea for 15 years.

But the mandate expired on April 30 after Russia vetoed a resolution for its renewal.

This prompted 49 countries and the European Union to issue a joint statement the following day that called for a new mechanism to replace the UN panel.

Kim Song said the US and other Western countries should deeply reflect on the failure of what he called their hostile policy toward North Korea. He added that if the US and "its followers persistently pursue the anachronistic hostile policy," they will face "a more miserable strategic defeat."

Sources with knowledge of North Korea told NHK that the end of the UN panel's mandate will facilitate the North's trade and enable the country to export more items, including underground natural resources.

Experts are voicing concern that the North will accelerate its sanctions violations.