The construction of eight Type 26 frigates will begin on the Clyde next summer.

The vessels were promised by David Cameron during the independence referendum and were seen as an inducement to get Scots to vote No.

The programme was later scaled back from 13 to eight and when junior defence minister Harriet Baldwin was asked for a start date in July, she admitted: "We do not know yet".

Visiting BAE Systems' shipyard in Govan on Friday, defence secretary Michael Fallon announced summer 2017 as the date the first steel would be cut.

He said the contract would secure hundreds of Scottish shipbuilding jobs for almost two decades.

Fallon said: "Backed by Britain's rising defence budget, the Type 26 programme will deliver a new generation of cutting-edge warships for our Royal Navy at best value for taxpayers.

"The UK Government's commitment today will secure hundreds of high-skilled shipbuilding jobs on the Clyde for at least two decades and hundreds more in the supply chain across Britain."

The project has been hit by delays, with plans for construction to begin earlier this year put back, and fears raised over shipbuilding jobs on the Clyde.

The UK Government's blueprint for the battleships was laid out in the 2015 strategic defence and security review.

Fallon has also announced a £100m contract with MBDA to deliver the Sea Ceptor self-defence missile system for the Type 26 fleet.

Scottish secretary David Mundell said: "This is a momentous commitment for Scotland that will strengthen and secure our shipbuilding industry on the Clyde for the future.

"The UK Government is backing jobs on the Clyde and in its shipyards - and this investment is only possible because of the broad shoulders of our strong UK defence budget."

The SNP warned UK ministers not to be "too self-congratulatory" after the delays, with defence spokesman Brendan O'Hara saying: "All they have done today is fulfil the promise they made last year, the one that replaced the promise they broke the year before."

The UK Government is said to have invested a total of £1.9bn to date in the Type 26 programme, which will replace the Type 23 frigates.

The incoming vessels will be on standby for deployment around the world and will be prepared to take part in active conflict and humanitarian rescue.

Details of the Type 31 - lighter frigates - building programme is still to be laid out, Fallon told BBC Radio Scotland's Good Morning Scotland programme.

BAE Systems said manufacturing contracts are already in place for the procurement of major equipment for the first three Type 26 ships.

There are currently 27 companies in the supply chain, working with BAE to deliver the ships, the firm added.

The defence secretary has also revealed MoD plans to sign a contract shortly to start building two offshore patrol vessels by 2019, a move he said will protect jobs on the Clyde before the Type 26 programme gets fully under way. Negotiations are expected to be concluded before Christmas.

GMB union regional secretary Gary Smith told BBC Radio Scotland the announcement was "fantastic news" but accused the UK Government of not fulfilling all its promises.

"We were told that there was going to be a frigate factory built on the Clyde which would allow us to deliver ships more efficiently, perhaps given us the ability to build ships that could have been exported, and Michael Fallon, in truth, was dragged kicking and screaming to this announcement today after we exposed the fact that his government planned to move some of the work down south.

"But, cutting through it all, fantastic news for the workforce and the economy of greater Glasgow as well."

The frigate programme was one of the centrepieces of Better Together's campaign for Scotland to remain in the UK in 2014. Unionist politicians said voting No would "ensure the future of Scotland's shipbuilding industry" and unveiled a poster conveying the same message.

SNP defence spokesman Brendan O'Hara welcomed the announcement but criticised the delays and downscaling of the project.

He said: "I'm obviously very pleased that the UK Government has at last come forward with a date for 'cutting steel' on the Type 26 frigate programme. It is something the SNP has been keeping up the pressure on the UK Government to do for the past few months.

"This project has been delayed for far too long already and the uncertainty surrounding the start of the project, amid rumours of a shortage of money at the MoD was causing serious concern among the workers.

"Today's announcement therefore, confirming that all eight Type-26 frigates are to be built in Glasgow is very welcome and is a massive tribute to the level of skilled worker that still exists in Glasgow's shipyards.

"Before the 2014 independence referendum we were of course promised that there would be thirteen of the Type-26s built on the Clyde, so I would caution the UK Government against being too self-congratulatory today, as all they have done today is fulfil the promise they made last year, the one that replaced the promise they broke the year before.

"When announcing the cut from 13 to eight Type-26's, the then Prime Minister David Cameron assured the workers at BAE in Glasgow that there would be five general purpose frigates (GPF) ordered to make up the shortfall. We now need to ensure that the commitment to building those five GPF is kept and that they are all built on the Clyde."