Efforts to free the Royal Navy's new £1.2bn nuclear submarine were under way today after it ran aground in shallow waters off the Isle of Skye.

Though no one was hurt, some local people said they were deeply concerned about the incident. The Royal Navy said it would fully investigate how the 100-metre long vessel became stuck on a shingle bank between the mainland and Skye.

The commanding officer, named as Andy Coles, could be court martialed as a result of the incident.

The coastguard was at the scene and an earlier attempt to tow the submarine failed, according to witnesses. Royal Navy vessels and a tug will try to free the submarine at high tide later today.

A spokesman for the Maritime and Coastguard Agency (MCA) said it was monitoring the situation closely. "We have sent a coastguard tug to where the submarine ran aground at the Kyle of Lochalsh near the Skye bridge," he said.

"It will stand by and monitor what will be going on. We think on the rising tide, at around 6pm, there should be some movement of the vessel."

The Ministry of Defence said this morning that the accident was not nuclear and that there was "no indication of any environmental impact".

HMS Astute has not yet entered service and is believed to have been undergoing sea trials when the incident happened.

The accident is embarrassing for the navy because the Astute has been billed as the stealthiest of submarines. One of its jobs when it comes into service next year will be to drop special forces discreetly ashore.

A navy spokesman said: "The incident occurred during a boat transfer from the submarine in confined water. The rudder went aground and it was held by the rudder on the rocks."

A defence source said it was likely that Coles, as the officer in ultimate charge of the submarine, would face a court martial.

John Laing, the councillor for the area, said there was concern about the incident locally.

"The people of Kyle and Broadford are well used to seeing both nuclear and conventional subs going up and down because of the torpedo testing range, so the sight of subs is not unusual. But of course we are deeply concerned that HMS Astute has gone aground and we just hope there is no danger. I would like to know what the circumstances were that caused it to come aground."

Laing said the incident highlighted the need for two sea-going tugs, operated by the MCA in Stornoway, on the Isle of Lewis, and on Shetland, to be kept in service. The vessels had been due to be withdrawn because of cuts, he said.

"The alarming thing is that these tugs are being withdrawn as a savings measure. This is exactly the kind of crisis that the tugs are out in place to help to respond to and there is huge concern about the removal of the tugs and I will be trying to co-ordinate a response to that," he said.

One witness, Rachel Browett, who runs the Bright Water Visitor Centre in Skye, said: "It's a concern. Anything with the word nuclear in it is obviously a worry, but I don't know enough about it to say more."

But Kyleakin community councillor Mike Taylor said most residents had been unruffled by the incident.

"The local population are not worrying about any nuclear problems," he said "We have lived with nuclear subs up here for 30 to 40 years."

He said he had driven past the stricken vessel at lunchtime. "There is a deep water channel there but it has obviously strayed from that," he said. "It's not helped by the fact that we have very low tides up here at the moment. If they don't manage to get it off at high tide, I don't know what they'll do."

The MCA said it was alerted to the incident at about 8.19 this morning.

The navy describes the Astute as "the largest, most advanced and most formidable vessel of its kind ever operated by the Royal Navy".

The submarine weighs 7,800 tonnes and is almost 100 metres (328ft) long.

It incorporates the latest stealth technology and boasts "a world-beating" sonar system with a range of 3,000 nautical miles, plus Spearfish torpedoes and state-of-the-art Tomahawk land attack missiles, according to the Royal Navy website.

Despite being far bigger than the Swiftsure and Trafalgar classes it is due to replace in 2011, the Astute requires fewer crew because of its advanced technology and automated systems.

Aside from attack capabilities, the submarine is able to sit in waters off the coast undetected, listening to mobile phone conversations or delivering the UK's special forces where needed.

The 39,000 acoustic panels that cover its surface mask its sonar signature, meaning it can sneak up on enemy warships and submarines, or lurk unseen and unheard at depth.

The submarine's nuclear reactor means that it will not need refuelling once in its entire 25-year life and it makes its own air and water, enabling it to circumnavigate the globe without needing to surface.

Built by BAE Systems at Barrow-in-Furness, Cumbria, it is the first in a fleet of six.

Scottish CND (Campaign for Nuclear Disarmament) expressed concern at the incident.

John Ainslie, the group's co-ordinator, said: "This is just the latest in a long line of incidents involving nuclear submarines off the west coast of Scotland. These vessels are regular visitors to the seas around Skye.

"The navy has several submarine trials areas near Raasay and Applecross.

"Inquiries into previous incidents have shown an appalling lack of common sense and basic navigation skills on these hi-tech submarines."

The accident happened almost exactly 50 years after the UK's first nuclear submarine was launched. HMS Dreadnought was launched on 21 October 1960 by the Queen.