Officials said they would not speculate as to why Beijing had ignored trade rules relating to Norwegian salmon. But it seems clear that the threat from the Chinese embassy in Oslo last year, of "damage" to diplomatic ties should the Nobel Prize be handed to "a criminal" has focused on a narrow, iconic target.

The Foreign Office said it was in talks with the WTO about how to proceed against China. "Norway believes the measures put in place by China are in conflict with international trade rules, and we have raised the issue in the WTO," said a spokesman. "We are now in a dialogue with Chinese authorities to resolve the issue, and we will continue to monitor the situation."