BANGKOK -- In their first interview since being detained by Thai authorities, the crew of a cargo aircraft traveling from North Korea said Sunday that they did not know they had been transporting an arsenal of rockets, grenade launchers and other unidentified weapons weighing at least 30 tons.

"They said it was oil drilling equipment," said Viktor Abdullayev, the plane's co-pilot. "That's what the manager told us," he said referring to his employer, a civilian cargo company from the former Soviet republic of Georgia.

Officials in Thailand did little over the weekend to shed light on the perplexing seizure of the aircraft, offering only rudimentary details about the plane, its crew and its cargo.

The five-man crew is to be charged in court Monday with possession of weapons of war, in a case that may shed light on the shadowy business of global arms trafficking -- and in North Korea's role, in particular.

Thai authorities said the weapons were seized after a tip from American officials, and said the shipment appeared to violate a United Nations arms embargo but did not provide a detailed accounting of the armaments, which will undergo a more thorough inspection Tuesday.

Thailand was acting, it said, under United Nations Resolution 1874, which was passed in June in response to nuclear tests in North Korea. The resolution is effectively an arms embargo covering the transport of heavy weaponry to and from North Korea. Such weapons sales are one of the few ways the country has been able to earn foreign currency.