Britain's defence ministry said the submarine was 'watertight' and there were no injuries to personnel [AFP]

A British Royal Navy nuclear-powered submarine has run aground off the coast of northwest Scotland, a spokesman at Britain's ministry of defence said.

"This is not a nuclear incident," the spokesman said on Friday. "There are no injuries to personnel and the submarine is watertight."

The ministry said it was "assessing the situation". The Maritime and Coastguard said it was alerted to the incident at about 0720 GMT and had sent an emergency tug boat to assist.

David Black, a consultant with Jane's Strategic Advisory Services in London, told Al Jazeera the vessel "is one of the new class of nuclear attack submarine for the navy and was launched in 2007".

"It's about 7,200 tonnes and is reportedly one of the most advanced ... submarines currently in service," he said.

"Initial reports that are coming out of the MoD indicate that they were transferring personnel ashore off the Isle of Skye, which means they were obviously on the surface.

"And they were probably trying to keep her steady in the face of a tide that was coming in or going out - I think going out, the ministry of defence said - [and] something happened obviously and it seems to have run aground."

The ministry of defence identified the boat as an Astute-class submarine.

As part of a major defence review unveiled on Tuesday, the government confirmed it would go ahead with an order for seven new Astute-class submarines, built by BAE Systems.

Source: Al Jazeera and agencies