The five - four from Kazakhstan and one from Belarus – were detained on December 12 last year on suspicion of weapons smuggling.

The five crew men will be deported to their home countries [AFP]
Their Georgian registered Ilyushin-76 cargo plane had landed at Bangkok's Don Muang airport on a refuelling stop en route from the North Korean capital, Pyongyang.

The men at the time said they were carrying oil drilling equipment bound for Ukraine.

But during the stopover Thai customs inspectors acting on an intelligence tip-off found the plane was loaded with around 35 tonnes of weapons, including missiles, rockets and grenades.

Al Jazeera's Aela Callan reporting from Bangkok said the murky nature of the case meant it had always been a headache for Thai authorities.

The final destination of the weapons has never been made clear, she said, and even though the crew will now be deported it remains unclear what will happen to the cargo of weapons.

Income earner

Several reports have speculated that the weapons were ultimately intended for Iran, although that has never been confirmed.

In recent years arms exports have become one of North Korea's main earners of foreign currency, selling weapons to several countries in the Middle East and anyone else willing to pay.

But under UN resolution 1874 passed last June, North Korea is banned form exporting any arms except light weapons.

The resolution followed international outrage over North Korea's testing last year of an intercontinental rocket and a nuclear warhead.

Under the terms of the resolution member states are mandated to monitor and intercept any shipments they suspect may be in contravention of the sanctions.