The Lida Demesh, carrying a consignment of cars from Japan, was heading for the Russian port of Vladivostok when it was stopped by patrol near Cape Musudan.

No reason was given for the search, but Russian sources said the ship may have gone too close to a missile test site.

A similar incident in 2005 took 15 days to resolve through diplomatic channels.

The ship had sought shelter from a storm in North Korean territorial waters.

Strong winds

On Saturday, an official at Vladivostok's maritime rescue centre, Vladimir Yeroshkin, said the Lida Demesh had been detained and boarded by the North Korean coastguard about 3-5 nautical miles (5.5km) from Cape Musudan.

This is a small two-hold ship - it is quite possible that weather conditions forced it to move closer to the coast

Vladimir Yeroshkin

Vladivostok Maritime Rescue Centre

"An armed group boarded the ship and ordered the captain to change course and go to a North Korean port [Chongjin]," he told the Russian NTV network.

Mr Yeroshkin said the centre had been told the ship's 25 crew-members were fine and that there had been no threat to their lives.

North Korean officials in Russia said they were not aware of the reasons for the detention, but Mr Yeroshkin said strong winds might have accidentally forced the vessel into North Korean territorial waters.

"The forecast for our region is a N-NW wind, 15-18 metres per second," he said.

"This is a small two-hold ship. It is quite possible that weather conditions forced it to move closer to the coast."

Most countries claim an area extending 12 nautical miles (22.2km) from their coast as territorial waters.