Police are warning people to stay away from an oil rig that was blown onto a remote Scottish beach in a storm.

The Transocean Winner drilling rig was being towed when it broke free of its tug and ran aground on the Isle of Lewis off Scotland's west coast on Monday.

Environmental groups have expressed concern, but coast guards say the risk of pollution is low. Salvage crews are working to recover some 280 tons of diesel on board.

Local politicians are calling for an emergency towing vessel to be based in Scotland's Western Isles after reports it took coast guards 18 hours to reach the rig.

Scottish National Party lawmaker Angus MacNeil says he also wants to know "why this oil rig was being towed in severe winds."