Two U.S. legislators have blasted the United Nations for neglecting hundreds of thousands of North Korean refugees hiding in China.

Senator Sam Brownback and Congressman Frank Wolf in April sent a letter to UN Secretary-General Kofi Annan on UN negligence on protection of human rights worldwide.

The Republican lawmakers pointed to the high insecurity suffered by North Korean refugees in China due to a lack of protective measures by the UN High Commissioner for Refugees.

Their urge reflects growing U.S. voices calling for the international community to address the worsening human rights situation in North Korea.

The North has detained an estimated 200,000 political prisoners, and between 200,000 to 300,000 North Korean refugees are believed to be hiding in China.