- The oil rig was blown ashore in stormy weather
- Anti-pollution organizations are monitoring the situation
The more than 19,000-ton drilling rig, Transocean Winner, was being towed west of Scotland's Isle of Lewis when it was hit by the harsh weather.
In a statement, the UK Maritime and Coastguard Agency (MCA) said it became detached from the tug boat around 4:20am BST and became grounded at Dalmore Beach near Carloway.
There was no one on board, but MCA's anti-pollution branch were monitoring the situation as the rig had 280 metric tonnes of diesel on board.
"The Maritime & Coastguard Agency's counter pollution branch and the SOSREP have both been monitoring the situation since yesterday evening and the local authority, police and Marine Scotland have all been kept informed," it said.
Resident Andrew MacLeod told CNN his neighbor woke up to a loud bang when the rig grounded.
An emergency vessel was deployed to assist the tug but despite their efforts, they were unable to reconnect the tow line.