Kursk timeline

12 Aug: Sinks during Barents Sea exercises 14 Aug: Russian navy inspects sub 15 Aug: Attempts to attach rescue capsule fail 16 Aug: Russians report no signs of life. Accept help from the West 17 Aug: British and Norwegian craft readied for rescue attempt 19 Aug: British and Norwegian teams arrive at scene 20 Aug: Norwegian and British divers examine Kursk 21 Aug: Divers enter flooded sub 22 Aug: President Putin arrives in Murmansk

The young fish come from the Barents Sea and can end up in Scottish fishing grounds the following summer.

Mr Duncan said: "Fish know no boundaries, they can travel great distances and herring from this affected area could be found in fishing nets and eventually onto the tables of Scots."

Environmentalists from Norway are monitoring radiation levels.

They say they have seen no signs of problems in the Barents Sea, but are currently examining samples at a lab in Oslo.

However, unconfirmed reports were made on Wednesday that radioactive contamination had been found a few kilometres from where the nuclear submarine sank.

'Radiation levels normal'

Russia's independent television station NTV said there was an increase in radiation levels on the coast near the site where the Kursk went down.

But the head of the Russian navy's main headquarters, Admiral Viktor Kravchenko, said radiation levels in the area were normal.

John Ainsley, from CND, Scotland, believes there could be about a tonne of uranium on the submarine.

The submarine remains underwater

"At the moment we are not talking about massive releases of radiation, but there is probably a small percentage of what was found after the Chernobyl accident.

"However, there is obviously a long-term potential for material to leak into the sea and affecting fish in the area and then into the food chain," said Mr Ainsley.

He added: "The reactor circuit material might well have broken in the explosion but if it hasn't and it is ruptured during the raising of the sub then that is creating additional problems."

Deeper water

There are currently two American and three other Russian submarines lying on the sea bed.

They do not pose the same problems as the Kursk because they are situated in much deeper water.

However, Mr Duncan said: "Fishermen rely on the health of the sea, anything which affects the health of the sea has an effect on consumer confidence of all fish stocks."

Ian Duncan: Scottish Fishermen's Federation

It is understood a number of farmers in Scotland are continuing to feel the affects of the Chernobyl explosion 14 years ago.

The world's worst nuclear disaster killed an estimated 30,000 people and contaminated grazing areas used by sheep being bred in Scotland.

The cause of the accident involving the 118-manned Kursk is still unclear.

Russian officials say they believe the submarine may have collided with a Western submarine that was in the Barents Sea to monitor a large naval exercise in which the Kursk was taking part.

Western experts say the damage to the submarine appears to have been caused by a catastrophic explosion in the torpedo bay.