North Korea said Wednesday that Cuban arms seized from a Pyongyang-flagged ship near the Panama Canal were part of a legitimate deal, amid concerns UN sanctions may have been violated.
Havana said the arms discovered on the ship among tons of sugar were "obsolete" Soviet-era missiles and parts sent to Pyongyang for repair -- an account backed up by their North Korean allies.
"This cargo is nothing but ageing weapons which are to be sent back to Cuba after overhauling them according to a legitimate contract," the North's Korea Central News Agency quoted the foreign ministry as saying.
"The Panamanian authorities should take a step to let the apprehended crewmen and ship leave without delay," the statement added.
But Panama has urged UN inspectors to scrutinise the cargo, which UN diplomats said could constitute a breach of the strict arms sanctions imposed on North Korea over its nuclear programme.
"The cargo is illegal because it was not declared. Anything that is not logged, even if it is obsolete, is contraband," Security Minister Jose Raul Mulino said.
"We are awaiting the arrival of experts from the United States and Britain, per our request, as well as a technical team from the UN Security Council," he added.
Panama said Monday it had discovered military equipment, which it believed to be missiles, after impounding the Chong Chon Gang and conducting a drugs search.
On Tuesday, Cuba claimed the shipment as its own, with the foreign ministry listing 240 metric tons of "obsolete defensive weapons", including two anti-aircraft missile systems, as being on board.
There were also "nine missiles in parts and spares," various Mig-21 aircraft parts and 15 plane motors, "all of it manufactured in the mid-20th century" and "to be repaired and returned to Cuba."
Panama President Ricardo Martinelli tweeted a photo of the haul, which experts said Tuesday was an ageing Soviet-built radar control system for surface-to-air missiles.
South Korea welcomed the seizure.
"If the shipment turns out to be in breach of UN resolutions, we expect the UN Security Council's sanctions committee to take relevant steps expeditiously," the foreign ministry said in Seoul.
In Washington, State Department spokeswoman Marie Harf said Wednesday that the US would raise the issue with Havana "very soon."
At the United Nations, diplomats said UN sanctions had likely been violated.
"Clearly the facts still need to be established," said Britain's UN ambassador Mark Lyall Grant, though he added: "On the face of it, the transfer of these weapons to North Korea would be a violation of the sanctions."
Diplomats said Cuba should have sought a waiver to transfer the weapons, if they are obsolete.
They also said North Korean sanctions panel experts would take up the case but that it could take months to investigate.
Defense and security consultants IHS Jane's said Tuesday that the photo tweeted by Martinelli appeared to show an "RSN-75 'Fan Song' fire-control radar system."
"One possibility is that Cuba could be sending the system to North Korea for an upgrade," the group said. "In this case, it would likely be returned to Cuba and the cargo of sugar could be a payment for the services."
Panamanian officials said Monday that the crew resisted the search, and that the ship's captain attempted to commit suicide after the vessel was stopped.
North Korea countered that the captain and crew had been "rashly attacked," condemning what it called a "violent action" by Panamanian investigators.
Reporters on Tuesday were taken aboard the vessel -- a rusting, dingy ship with a dank kitchen. The only reasonably appointed room was the captain's quarters.
The ship was sailing from Cuba with a crew of about three dozen when it was stopped by drug enforcement officials and taken into port in Manzanillo.
"The world needs to sit up and take note: you cannot go around shipping undeclared weapons of war through the Panama Canal," Martinelli told Radio Panama Monday.
Analysts in Seoul said the North was fully capable of providing missile repair services for other countries.
"But we cannot rule out the possibility of North Korea importing parts for its own Soviet-era missiles", Shin In-Kyun, president of the private Korea Defence Network, told AFP.
North Korea's army chief of staff, General Kyok Sik Kim, visited Cuba last month and said the two countries were "in the same trench".
Pyongyang carried out a third nuclear weapons test in February, triggering tighter UN sanctions, which bar the transport of all weapons to and from North Korea apart from the import of small arms.
Five percent of the world's commerce travels through the century-old Panama Canal, with that expected to increase following the completion of a major expansion project.