The rig, operated by Stena Drilling, is carrying out work for StatoilHydro at the Troll field. The rig was not connected to any well when the incident occured.
There are 100 people on board. No injuries are reported as a result of the smoke and sparks.
StatoilHydro has mustered its emergency response organisation and has helicopters and standby vessels in the area.
Weather conditions are favourable.
A telephone number for relatives has been set up:
Stena Drilling: +47 55 91 80 16