A diesel oil leak could have caused the fire which hit Statoil's Sleipner A platform on the evening of 18 October.
This conclusion has been drawn by the group's own investigators on the North Sea installation, reports platform manager Thormod Hope.
He emphasises that no final decision has been reached on the cause of the fire. Police and officials from the Norwegian Petroleum Directorate arrived on Sleipner A yesterday and an inquiry is now in full swing.
"It looks as if diesel oil escaped from a tank," Mr Hope explains. "The heat from the exhaust pipes in a power station could have ignited this fuel."
Setting a date when gas and condensate production can resume from the Sleipner area is difficult, he adds. Repairs cannot start until the police and the NPD have completed their investigations.