BANGKOK – Thailand said Monday that an aircraft loaded with North Korean weapons was flying to Iran when it was intercepted in December but the ultimate destination of the arms is still not known.

Thai authorities seized the Ilyushin Il-76 cargo plane and its five-man crew as it landed to refuel on a flight from Pyongyang Dec. 12. Found on board were 35 tons of weapons.

A Thai government report to the U.N. Security Council, leaked to reporters in New York over the weekend, said the aircraft, which had violated U.N. sanctions against North Korea, was bound for Tehran's Mahrabad Airport.

But Thai government spokesman Panitan Wattanayarkorn said Monday that "to say that the weapons are going to Iran, that might be inexact."

"The report only says where the plane was going to according to its flight plan, but it doesn't say where the weapons were going to," he said. "It's still under investigation, and the suspects are under our legal system."

The five-man crew four from Kazakhstan and one from Belarus remain under detention. The crew has been charged with illegal arms possession, but the charges are expected to be stiffened once the investigation wraps up, police have said.

The weapons found on board the aircraft were reportedly light battlefield arms, including grenades hardly the ones Iran's sophisticated military would need.

From the start there has been speculation that the weapons were to be shipped on to some of the radical Middle Eastern groups supported by Tehran.