Shares in Leroy Seafood, which relies heavily on exports, suffered most from disappointment that Norway had failed to persuade Russia to drop the ban and were down 4.5 percent at 69.75 crowns by 1250 GMT on the Oslo bourse.

Fjord Seafood shares were down 2.9 percent at 4.32 crowns, Cermaq fell 1.4 percent to 54.0 crowns and Pan Fish was down 1.0 percent at 2.07 crowns. The benchmark index was up 0.35 percent.

Fish farming stocks had gained last week on hopes that the threatened import ban would be averted by the New Year.

"It will take more time to get this solved," said Klaus Hatlebrekke, an analyst at Norwegian bank DnB NOR Markets. He reckoned that it would take until late January or early February to resolve the dispute.

Moscow is locked in a far bigger trade dispute with Ukraine over natural gas exports.

Norway farms about 570,000 tonnes of Atlantic salmon a year out of a world total of 1.25 million tonnes. Seafood is Norway's biggest export earner behind oil and gas and metals.

Russian vets said they found lead 18 times above safety levels in Norwegian salmon and cadmium 3.5 times higher. They also said that Norway's monitoring standards were inadequate.

EXPORTS LEAP

Russia is a relatively small but fast-growing fish export market, but a health scare could harm exports to other countries. Norway exported about 17,000 tonnes of fresh salmon to Russia in 2004, up from 8,700 tonnes in 2003.

"We have to go into a dialogue with them and convince them that the fish is safe...because it is," Fisheries Minister Pedersen told independent TV2 on Monday.

Norway plans to send a senior ministry official to Russia for talks on Jan. 12, after Russian Orthodox holidays.

The Norwegian Food Safety Authority said that it wrote to Russia on Dec. 28 offering greater monitoring of exports. "We are awaiting a Russian reply," said Finn Oluf Nyquist, spokesman of the authority.

"We have no explanation of the finds made by Russian veterinary authorities," he said.

The authority said Norway had checked 125-375 salmon a year for cadmium and lead since 1998, or 40-75 sites each year. All results have been far below maximum EU permitted levels, it said.