The Gaul sunk in heavy seas in 1974 with 36 men aboard

The Gaul, a fishing vessel based in Hull, was lost off the Norwegian coast on 8 February, 1974.

Investigations concluded the boat sunk after being battered by heavy seas.

But suspicions have lurked for almost 30 years that the trawler could have been sunk by a Soviet Union submarine because there was a spy on board.

In 2002, four sets of human remains were raised from the wreck of the Gaul.

We have an unidentified set of remains. If you believe the spying theory, this could mean there was somebody else on board. Solicitor Barry Tindall

Three samples have been positively linked to known crewmen, but a fourth set are still unidentified.

Solicitor Barry Tindall, who represents the Gaul Families' Association, said 35 of the 36 families had provided DNA samples to aid the identification of bodies found in the wreck.

Samples from the 35th family are awaiting analysis after being taken last week but the final family had declined to take part.

But Mr Tindall said both families hold the key discovering whether the final body is that of a crewman - or a possible spy.

He believes the final remains either belonged to men related to these two families or were those of another, unidentified person.

Inquiry due

Mr Tindall said: "There were two families who had not given DNA samples. Because this fourth set of remains was still unidentified it meant it was important to try to contact these two families.

"We've now done that and one has agreed to give DNA samples and that was being done on Friday.

"The other family, because of their own personal circumstances, did not want to give a sample."

He added: "There has always been this speculation about the Gaul and whether she was involved in spying.

"We have an unidentified set of remains. If you believe the spying theory, this could mean there was somebody else on board."

A full inquiry into the sinking of the Gaul is due to start in Hull on 13 January 2004.