The drilling rig Transocean Winner is being monitored by a counter-pollution team after grounding on the western side of the Isle of Lewis in the early hours of Monday.
The semi-submersible rig became detached from its tug during a towing operation. Severe weather prevented the crew of the Alp Forward from reconnecting the tow line.
No-one was on board the rig when it grounded at Dalmore beach near Carloway, the Maritime and Coastguard Agency said.
The beach is said to be a popular visitor area but coastguard teams and Police Scotland are now enforcing restricted access to the site to ensure specialist equipment can reach the scene.
Environmental groups have raised concerns about the incident but the coastguard said the pollution risk was believed to be low.
UK Coastguard commander Mark Rodaway said: ‘We understand that this incident is of interest to people living in the area, but we’re really asking them to stay away to ensure easy access for emergency services and salvors.
‘’Also the last thing we want is for people to be injured or worse trying to get a closer look on remote cliff paths.’’
The UK government is responsible for managing the response with Hugh Shaw, the Secretary of State’s Representative for Maritime Salvage and Intervention, travelling to Lewis.
Local politicians have united in a call for an emergency towing vessel to be reintroduced for the Western Isles.
SNP MP Angus MacNeil campaigned on the issue after the previous emergency tow was removed.
He said: ‘’This could have been a very different outcome, and it is another example of why we need to have an emergency towing vessel on the west coast of Scotland.
“The UK government must return the ETV to Stornoway - a tug is an insurance policy for an unusual but possible event.
‘’I am also calling on the UK government to carry out an immediate investigation as to why this oil rig was being towed in severe winds west of the Hebrides and I’m seeking further details regarding the response time - which the Maritime and Coastguard Agency has said took 18 hours.’’
Highlands and Islands Labour MSP Rhoda Grant said: ‘’The one remaining emergency tug that covers the north and west coast is based in Orkney and takes an estimated eight hours to reach the north Minch and a staggering 12 hours to reach Barra Head from its Orkney base.
‘’Just two days after the tug was removed from Stornoway in March 2012, a cargo ship ran aground on North Uist. There was no loss to life on that occasion either, fortunately, but we cannot simply rely on good fortune to protect staff, passengers and our environment from any future disasters.’’
DOWNLOAD THE SCOTSMAN APP ON ITUNES OR GOOGLE PLAY