BANGKOK, Thailand — Thailand said Thursday it had decided to drop a case against the five member crew of a plane carrying sanctions-busting weapons from North Korea.

"The trial here will not benefit Thailand so we have decided to drop the charges," said Thanapich Mulapruk, spokesman for the Office of the Attorney General, in a statement.

"Their countries of origin want to try the men in their home countries," he said.

Another official from the attorney general's office said the Belarussian pilot and four Kazakh crew would not be formally extradited.

"(We) are sending an official to file a petition with the court to release all five men," Kayasit Pissawanprkan told reporters. "This is not an extradition but we consider them as having entered (Thailand) illegally."

No decision has been taken on what to do with the seized haul, which arrived on December 11 when the crew requested to land their Russian-made Ilyushin-76 plane at Thailand's domestic Don Mueang airport for refuelling.

The men claimed they were carrying oil drilling equipment bound for Ukraine.

The 35-tonne cargo, which included missiles and rocket-propelled grenades, is being held at an air force base north of Bangkok.

"The plane landed to refuel. Those arms were not aimed at attacking Thailand so the trial does not benefit (us)," added Thanapich.

Police had charged the five men with possessing illegal weapons and ammunition, smuggling weapons and other banned products and failing to report the cache.

Kazakhstan and Belarus both petitioned Thailand to ask for their nationals to be released for trial in their home countries.

A flight plan obtained by investigators showed the plane was bound for Iran, while US intelligence chief Dennis Blair has said that it was headed for an unspecified Middle Eastern destination.

The United Nations banned all North Korean arms exports in a tougher resolution passed in June following the North's latest missile and nuclear tests.

The Bangkok case is believed to be the first airborne arms cargo from Pyongyang to have been seized since then.

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