With all production now at a halt, Norway cannot even import from neighbours Sweden or Denmark, because its truck drivers are also on strike.

The 2,560 striking full-time brewery staff fear that a growth in temporary workers may undermine job security.

They are especially concerned that Norway may be flooded with cheap labour from the new EU member states in eastern Europe.

Thirsty

For although Norway is not a member of the EU, it is part of the wider European Economic Cooperation free labour market.

A Norwegian beer drinker laughs - nervously

The trade union that represents the full-time brewery workers - the Norwegian Food and Allied Workers Union - wants the ability to veto hiring decisions, but employer representatives have refused to budge.

"We cannot allow employees to have a veto right when it comes to these matters, said Carl Roenneberg, director for the Federation of Norwegian Food and Drink Industry.

The strike is also stalling production at factories that produce soft drinks, and both these and beer supplies could run out if the walkout lasts beyond a few days, commentators say.

Arild Oliversen, a union spokesman, told the BBC’s World Business Report that he expected to win, but that the strike could take months.

The separate truck driver strike has left most of Norway’s grocery stores almost empty of eggs, butter and cheese.