The carriers will be made on the Clyde and at Rosyth

The �3.8bn order for the Royal Navy carriers will be completed at yards on the Clyde and at Rosyth.

The Scottish Chambers of Commerce said the decision showed that Scotland could compete effectively in a global market.

SNP deputy leader Nicola Sturgeon, the MSP for Govan, said it was "great news" for her constituency.

BAE Systems' Govan and Scotstoun yards, which employ 3,000 people, will be among the companies to construct the ships.

The new 65,000-tonne carriers called HMS Queen Elizabeth and HMS Prince of Wales should enter service in 2014 and 2016.

This news will not only stabilise thousands of jobs on Clydeside but will also create in time many opportunities for hundreds more Jim Moohan Confederation of Shipbuilding and Engineering Unions

Ms Sturgeon said: "The Govan yard has a bright future and this order goes a long way to confirming that shipbuilding will continue on the Clyde.

"It is a testament to the hard work and skills of the workers at BAE that this contract has been won and provides a secure base for building a successful future."

Jim Moohan is a senior organiser for GMB Scotland's manufacturing section and chairman of the Confederation of Shipbuilding and Engineering Unions.

He said: "This news finally supports the financial investment that BAE Systems have placed in the skills and training at the Clydeside yard with apprenticeships and design staff.

"The workforce on Clydeside should be congratulated for adapting to the changing face of shipbuilding within the UK.

"Their commitment over the last 10 years in which the future of shipbuilding was in doubt should not be forgotten.

'Welcome news'

"This news will not only stabilise thousands of jobs on Clydeside but will also create in time many opportunities for hundreds more."

Jack Dromey, deputy general secretary of the T&G section of Unite, the trade union, said: "This is putting into practice what the unions have argued for years: government orders and taxpayers' money are vital for British manufacturing."

Glasgow North West MP John Robertson said the move would safeguard jobs.

He said he and his Labour colleagues had fought for some time for the carriers to be built in these yards.

He added: "I am pleased to see it will take place."

Liz Cameron, executive director of the Scottish Chambers of Commerce, said this had been the "most welcome news for Scotland's engineering sector in a very long time".