This undated photo released by the U.S. Justice Dept. May 9 shows the North Korean cargo ship Wise Honest. The Trump administration said it had seized the North Korean vessel that U.S. officials say was used to transport coal in violation of international sanctions. (Yonhap)

North Korea's top envoy to the United Nations sent a letter to U.N. Secretary-General Antonio Guterres, Friday, criticizing the United States' recent seizure of a North Korean cargo ship that Washington alleged violated international sanctions, Pyongyang's state media reported Saturday.

In the letter, Ambassador Kim Song called the seizure an "unlawful, outrageous and sovereignty-infringing" act, which he said indicated the U.S. was "indeed a gangster country," according to the Korean Central News Agency.

The U.S. Justice Department said May 9 that it had seized the 17,061-ton Wise Honest for allegedly transferring coal and machinery while at sea, in violation of the sanctions, in the first such direct action.

"Recently, the U.S. committed an unlawful and outrageous act of taking the DPRK's cargo ship to Samoa, linking the ship to the violation of American domestic law, and this act of dispossession has clearly indicated that the United States is indeed a gangster country that does not care at all about international laws," the North's permanent representative to the U.N. wrote in the letter.

DPRK stands for the North's official name, the Democratic People's Republic of Korea.

"Moreover, the United States committed a sovereignty-infringing act of flagrantly violating the UN Charter by dispossessing the cargo ship where the DPRK's sovereignty is fully exercised," the envoy added.

Kim also called on the U.N. chief to take "urgent measures," saying international concern was growing over the likely impact on the peninsula to be caused by the "heinous act" committed by the U.S.

"I believe that the Secretary General of the United Nations is requested to take urgent measures as a way of contributing to the stability of the Korean peninsula and proving the impartiality of the U.N.," he said.

"We will follow actions to be taken by the U.N.," he added.

The seizure added to the uncertainties over the prospects for the resumption of stalled nuclear talks between Washington and Pyongyang.

Their negotiations have hit an impasse since the second summit between U.S. President Donald Trump and North Korean leader Kim Jong-un in Hanoi in February ended in a failure due to an inability to bridge gaps over the scope of Pyongyang's denuclearization and Washington's reciprocal sanctions relief. (Yonhap)