Radioactive discharges from the Dounreay nuclear plant in Caithness triggered a fierce row with Norway in 1990, according to official files just released by the Scottish Government.

Norwegian ministers made strong representations to the UK Government in protest at discharges that they said threatened their fishing industry. This prompted a flurry of memos within the UK Government, expressing concerns that the UK wasn't doing enough to refute the Norwegian accusations.

Malcolm Rifkind, the Conservative Secretary of State for Scotland at the time, wrote to the British ambassador in Oslo, David Ratford, agreeing that more "pre-emptive action" should be taken.

"By its very nature the subject of radioactive waste attracts biased and inaccurate media coverage, which results in the creation of widespread concern both at home and abroad," he wrote. "We should certainly do what we can to minimise that."

Rifkind was backed by a senior Foreign Office official, who complained that "we have often found ourselves reacting to Norwegian criticism", and said that the Government seemed to lack the necessary information to counter the criticisms.

He claimed the "propaganda" put out by anti-nuclear groups was "scientifically illiterate", but would be widely publicised "and we must take positive steps to counter it".

One proposal was to invite the Norwegian environment minister, Kristin Hille Valla, to visit Dounreay. But this would leave her "open to the temptation to play to the environment and anti-nuclear constituencies here", warned a cable from Ratford in August 1990.

He urged postponing any invitation to Halla on the grounds that her position in the Norwegian government was insecure, and she could be the casualty of any reshuffle.