An oil rig that ran aground in the Western Isles is being towed to safety.

The Transocean Winner broke free while being towed to Malta on August 8 and grounded on Lewis, spilling 53 tonnes of diesel into the sea.

The rig was towed off the rocks at high tide on Monday night and is now on a 54-mile journey to a harbour on the other side of the island.

The 17,000-tonne vessel is expected to arrive at Broad Bay in the early hours of Wednesday morning.

Hugh Shaw, the secretary of state's representative for maritime salvage and intervention, told BBC Radio Scotland: "We'd anticipated if we got her safely off we were looking at perhaps two to two-and-a-half knots to get her round the 54-mile passage.

"I spoke to the salvage master this morning. They're making steady but slower progress than we had anticipated so she's actually doing about 1.7 knots.

"So I'm not expecting her to arrive in Broad Bay now until perhaps the early hours of tomorrow morning."

Eight anchors are being laid out in the harbour to hold the rig in place once it arrives.

Minor repairs could be made in Broad Bay but a semi-submersible ship may be needed to transport the rig if more serious engineering work becomes necessary.

Mr Shaw added: "There may be the opportunity to effect some temporary repairs in Broad Bay itself but that would only be very light engineering if we do anything there."