Sixty-nine Patriot missiles impounded in Finland after being found on a merchant vessel in mid-December were headed for South Korea, the Finnish government said Wednesday, granting their transit through Finnish territory.

"The missiles in question had been sold to the Republic of Korea by Germany," the government said in a statement, adding that it had granted a licence to Seoul's "Defence Acquisition Programme Administration to transit through Finnish territory 69 Patriot missiles."

The surface-to-air missiles, produced by US firm Raytheon, were discovered on December 15 aboard the British-registered Thor Liberty docked in the southeastern Finnish port of Kotka.

Confusion initially surrounded the shipment.

Finnish police said the goods were bound for China but did not have the necessary authorisation to pass through Finland, while a German defence ministry spokesman said the missiles came from the German military and were destined for South Korea.

The spokesman said it was a "legal sale on the basis of an accord between two states at the government level" and that export authorisations were in order.

However a senior Finnish defence ministry official said Finland had not received any transit licence application for the missiles from Germany.

A joint team of Finnish customs and police officials removed and impounded the missiles during an investigation for suspected illegal export of defence material.

The vessel's Ukrainian captain and first mate were also detained for questioning and later slapped with a travel ban which is still in effect.

Last week the customs service said it planned to widen the investigation.

"Next week... we will want to hear more suspects or persons of interest in the case. It is possible there may be others of interest," the head of the Finnish customs anti-crime unit, Petri Lounatmaa, told AFP.

Finnish transport safety officials have cleared the Thor Liberty to leave Finland, but the vessel has remained in port due to the travel ban imposed on its first officers, and the removal of its cargo.