Norway could block any UK attempt to rejoin the European Free Trade Association, the small club of nations that has access to the European single market without being part of the EU.
Senior Norwegian government members are to hold talks with David Davis, the Brexit minister, in the next few weeks.
Some Brexit supporters have suggested that Efta would be one way of retaining access to the single market while honouring the referendum mandate to leave the EU.
Norway is not a member of the EU, but it has access to the single market from its membership of the European Economic Area (EEA), which groups all EU members and three of the four Efta members: Norway, Iceland and Liechtenstein, but not Switzerland.
Norway’s European affairs minister, Elisabeth Vik Aspaker, reflecting a growing debate in the country following the Brexit vote in the UK, told the Aftenposten newspaper: “It’s not certain that it would be a good idea to let a big country into this organisation. It would shift the balance, which is not necessarily in Norway’s interests.”
She also confirmed that the UK could only join if there were unanimous agreement, thereby providing Norway with a veto.