North Korea said Wednesday that Mexico has "forcibly detained" one of its ships months after it ran aground off Mexico's Gulf coast last year, and Pyongyang blames the United States for preventing the ship's release.

The head of a U.N. panel of experts, however, said the ship, the Mu Du Bong, is owned by a North Korean company that is under U.N. sanctions and should be "frozen," and that the panel has received excellent cooperation from Mexico in tracking the company and its assets.

"In the case of the Mu Du Bong, the evidence is overwhelming," Hugh Griffiths told The Associated Press in an email. The U.N. sanctions were imposed in response to North Korea's nuclear and missile programs.

The ship's parent company, Ocean Maritime Management Co., was sanctioned last July after Panamanian authorities found two Cuban fighter jets, missiles and live munitions beneath a cargo of sugar in another ship the company operated.

OMM responded by simply renaming 13 of its 14 vessels in an effort to avoid detection, the panel reported in February. North Korea has a history of using front companies for that purpose. None of the ships had been frozen by U.N. member states as recommended, the panel said at the time.

North Korea's deputy permanent representative to the U.N. told reporters Wednesday that his country will take unspecified "necessary measures to make the ship leave immediately."

An Myong Hun said the Mu Du Bong is strictly a commercial ship. He denied that the ship was carrying anything prohibited by U.N. sanctions and said it has no relations with OMM.

The North Korean diplomat also said Mexican authorities in January had decided to release the ship but "suddenly" revoked its decision. The U.N. panel's report, released in February, said the experts had informed Mexican authorities that the ship is an OMM asset.

The ship ran aground last July and damaged nearly an acre of coral reefs. The North Korean embassy in Mexico was asked to post a 10-million peso ($770,000) bond for any damage assessment. The North Korean diplomat said his country has paid the necessary fees and has "no legal obligation" to wait to move the ship.

Ricardo Alday, political coordinator for Mexico's mission to the U.N., said in an email that Mexico is not forcibly detaining the ship and that his country is fulfilling its international obligations. He said the 33 North Korean crew members "have absolute freedom of movement" and sleep in a hotel in the port of Tuxpan, where the ship is anchored.

The North Korean diplomat said the U.S. was responsible for pressuring Mexico to hold the ship.

A diplomat with the U.S. mission to the U.N. later responded, "As much as North Korea wants to make this about the United States, this is the determination of the 1718 Panel of Experts," which monitors compliance with U.N. sanctions. The diplomat spoke on condition of anonymity because they were not authorized to speak publicly.