In 2012, the Canadian company Couche-Tard bought Statoil Fuel & Retail, which manages distribution and pump stations for state-owned petrol giant Statoil and which is one of the world's biggest fuel distribution companies in the world.
On Thursday, business newspaper Finansavisen reported that the costs of keeping the administrative staff in Oslo was potentially problematic.
"We'll have to fight for our jobs in the future. Of course we are worried," said staff union representative Ketil Johannessen.
"The most likely thing to happen is that admin jobs are moved."
Joannessen told the paper that there was already a tense atmosphere in the company, as Couche-Tard has moved the company's logistics department to Riga.
Statoil Fuel & Retial press spokeswoman Karen Romer said there were no concrete plans for further moves, but said the company always kept an eye on the bottom line.