Defence Secretary Philip Hammond will today announce an additional £350 million-of funding for the next stage of designing the future generation of British nuclear-armed submarines.

This investment will sustain 1200 UK jobs and follows the initial £350 million of design work announced earlier this year, the Ministry of Defence said.

Mr Hammond will make the announcement during a visit to the Clyde Naval Base at Faslane.

Commenting on the Scottish independence debate, the Defence Secretary reiterated the Government's commitment to keep the base in Scotland, saying he was "confident" Scottish people would choose to remain part of the UK.

He said: "We are confident that the Scottish people will choose to remain part of the United Kingdom. The Faslane complex is the largest employment site in Scotland with over 6500 jobs underpinning the local economy.

"We have no plans to move the nuclear deterrent from the Clyde. On the contrary, we intend to move the Astute and Trafalgar Class attack submarines to Faslane, creating a further 1500 jobs. The Scottish Government needs to explain how their policy would benefit Scotland's economy and safeguard jobs."

The announcement followed the successful firing of an unarmed Trident ballistic missile by HMS Vigilant during a test launch in the Atlantic Ocean last week.

HMS Vigilant is one of four Vanguard Class submarines which maintain the UK's nuclear deterrent.

The Vanguard submarines will be replaced from 2028 by the Successor, which is currently being designed by British companies.

As a result of today's announcement, BAE Systems will get an additional £315m of work, with a further £38m carried out by engineering company Babcock.