An oil rig is at risk of grounding off the Isle of Lewis after high winds hampered a towing operation.

The semi-submersible drilling rig Transocean Winner became detached from the tug Alp Forward during severe weather conditions overnight.

There are no personnel on board the rig and there is no risk to life, the Maritime and Coastguard Agency said.

A spokesman said: "At 4.20am the master of Alp Forward reported that the tow line had parted and, due to the severe weather conditions, was unable to reconnect the tow line and the rig is at risk of grounding on the west side of the Isle of Lewis near Carloway.

"The tug Alp Forward remains on scene to visually monitor the rig."