The Panama government has said that the undeclared shipment of Cuban weapons found on board a North Korean ship are a "violation" of UN sanctions against arms transfers to Pyongyang, citing a UN report.

The ministry of public safety said in a statement on Wednesday that according to a draft report by UN experts sent to Panama after the seizure of the ship in July, the cargo "undoubtedly violates the UN sanctions".

The ministry statement was the first information released about the mission of the experts, who completed their inspections two weeks ago.

A source in the public security ministry said authorities had been given a first draft of the report compiled by UN sanctions panel experts.

North Korea is under UN sanctions over its controversial nuclear programme.

Those measures bar the transport of all weapons to and from the isolated state apart from the import of small arms.

North Korea carried out a third nuclear weapons test in February, triggering even tighter UN sanctions.

'Obsolete' weapons

The ship, the Chong Chon Gang, was intercepted on July 10 as it tried to enter the Panama Canal on suspicion it was carrying drugs.

Authorities instead uncovered 25 containers of military hardware, including two Soviet-era MiG-21s, air defence systems, missiles and command and control vehicles, buried under tonnes of sugar.

Both Havana and Pyongyang said they were "obsolete" Cuban arms being shipped to North Korea for refurbishment under a legitimate contract.

The UN has not stated publicly yet how it will proceed.

The ministry statement was released after a group of North Korean diplomats visited the ship's 35 crew members, who are being detained at a former military base on charges of arms trafficking.

The crew members face up to 12 years in prison if convicted.