North Korea's top envoy to the United Nations on Tuesday redoubled calls for the United States to quickly return a North Korean cargo ship seized on suspicion of violating international sanctions.

Kim Song, the North's permanent representative at the UN, also said that Pyongyang will "sharply watch every move of the US" while stressing that the US should think about the consequences the seizure could have on future developments.

On May 9, the US Justice Department said that it had seized the 17,061-ton Wise Honest bulk carrier, a vessel suspected of violating US domestic law and international sanctions, in the first direct seizure of a North Korean ship by American authorities.

"The United States should deliberate and think of the consequences that its out outrageous act might have on future developments, and also the United States must return our cargo ship without delay," he told a press conference at the UN headquarters

in New York.   He also said that his country is condemning "in strongest terms" the seizure of the ship because it is an "early product of extreme hostile policy of the United States against the North.

"Unilateral sanctions and extraterritorial application of national jurisdiction of a third country cannot be justified in any case, and in any circumstances and under the international law," he said.

Last Friday, Kim sent to UN Secretary-General Antonio Guterres a letter in which he called for "urgent measures" while describing the seizure as an "unlawful and sovereignty-infringing" act, which he said indicated the US is "indeed a gangster country."

Washington said that the Wise Honest was used to illicitly ship coal from the North and to deliver heavy machinery to the communist state, while payments for maintenance, equipment and improvements of the vessel were made in US dollars through unwitting US banks.

UN Security Council sanctions bar the North from transfers of coal and other goods.

A 2016 US sanctions act prohibits North Korean entities or individuals involved in illicit weapons proliferation activities from using the US financial system.

In April last year, Indonesian authorities first intercepted and seized the Wise Honest, which was later taken into custody by the US.

Analysts here said that the envoy appears to be making an implicit call for a scrapping or easing of the overall sanctions regime that has crippled the North's economy and threatened to derail its leader Kim Jong-un's policy drive to tackle pressing bread-and-butter issues.

They also said that the ship seizure has added to growing uncertainties over ongoing efforts to resume nuclear talks between Washington and Pyongyang amid fears that the regime could veer toward a provocative tack.

The talks have hit an impasse since the second summit between US President Donald Trump and the North Korean leader in Hanoi in February collapsed due to differences over the scope of Pyongyang's denuclearization and Washington's sanctions relief. (Yonhap)