More than 70 workers have been transferred off the Bruce platform east of Shetland following a loss of power late last night, the coastguard said.
Two coastguard rescue helicopters from Shetland and Inverness were mobilised to take non-essential staff off the installation.
The coastguard said 76 people were taken to other platforms in the area and that 45 remain on Bruce.
A spokesman for BP said: “BP can confirm it initiated a partial down-man of the Bruce platform following a loss of power on Thursday evening.
“Of the 121 people on board, 76 non-essential personnel have been taken off the platform.
“BP has been working closely with the Maritime and Coastguard Agency to transfer these people by helicopter to the East Brae and Heimdal platforms, the Alvheim FPSO and the Transocean Arctic drilling rig.
“The remaining 45 people on board Bruce are safe, production has been temporarily shut-in and work to restore power is on-going.”