Norwegian employers have threatened to lock out striking oil workers from offshore platforms from Monday.
That move that would shut off almost all the oil and gas output from the world's third largest crude exporter.
Unions said they would keep up the strike "as well as possible" and accused employers of gambling that the centre-right government would order an end to the strike rather than risk a halt to Norway's three million barrels per day output.
Mr Per Terje Vold, director-general of employers' group the Norwegian Oil Industry Association, said the strike that began last Friday was deadlocked, with no prospect of a negotiated settlement.
"A stoppage will lead to an almost complete shutdown of oil and gas production," Norway's state-dominated oil firm Statoil said of the strike over pensions.
Unions are already cutting about 375,000 bpd of Norway's 3.0 million bpd output and have unveiled plans to raise the strike to curb 700,000 bpd from Sunday night.
The Norwegian government said it would closely assess the consequences of the lockout. Oil accounts for about 20 per cent of Norway's gross domestic product.
In London, Brent crude futures were up 12 cents a barrel at $35.15.