Thailand will submit to the United Nations next week the results of an investigation into the seizure of a cargo plane carrying North Korean weaponry, the Thai prime minister said.

An Il-76 plane carrying 35 tons of weaponry was seized during refueling at Bangkok''s Don Muang airport on December 12. Officials said the arms included missiles and rocket-propelled grenades.

Abhisit Vejjajiva said: "The results of the investigation will be sent to the UN, and only then will we be able to decide whether to destroy the weapons, or take possession of them for the use of the Thai armed forces."

The report for the UN relates to the plane and its cargo, but not to the Kazakh and Belarusian crew of the plane who are being held in custody.

Arms trafficking experts researching the incident were earlier quoted by the Wall Street Journal as saying the flight plan for the plane showed that after Bangkok it was due to make refueling stops in Sri Lanka, the United Arab Emirates and Ukraine before unloading its cargo in Tehran.

Iranian officials have not yet commented on the allegation.

The paper said the plane stopped at an air force base in Azerbaijan en route to Pyongyang, but that the nature of that stop was unclear.

The crew of the plane have said they were unaware of the military nature of the cargo.

UN resolutions prohibit the export of large-scale weapons from North Korea, which is under international sanctions.