VIDEO: Work on Type 26 frigates to begin on the Clyde next summer.
Defence Secretary Michael Fallon says the date for cutting first steel will protect hundreds of skilled jobs until 2035.
Work to build a new fleet of Navy frigates will begin next summer, with Defence Secretary Sir Michael Fallon saying the construction of the "most advanced combat ships on the planet" will keep shipbuilding jobs on the Clyde for the next two decades.
Steel will be cut for the first of the eight Type 26 global combat ships next summer, with the project expected to last until 2035.
The Defence Secretary announced the news as he visited BAE Systems' shipyard in Glasgow.
Fears over the future of the yard were raised earlier this year after the work was delayed, with Scottish First Minister Nicola Sturgeon previously accusing the Ministry of Defence (MoD) of breaking a promise to workers there ahead of the 2014 independence referendum.
But Sir Michael said: "There are billions of pounds of work here for the Clyde, keeping the shipyards here in work for the next 20 years."
He added: "This Government is firmly committed to shipbuilding on the Clyde and the programme that will take us through to 2035. I would hope that would be one thing that the First Minister could actually welcome.
"We're investing in Scotland on the basis that Scotland will be staying in the United Kingdom."
Sir Michael told workers at the shipyard that the "growing defence budget" meant the UK Government has "reached agreement in principle with BAE Systems to turn our Type 26 ambition into reality and that the first steel cut will now take place next summer".
The UK Government minister said: "We have the highest regard for the capabilities that are demonstrated here day in day out on each succession of Royal Navy vessels, so by investing now in the most advanced combat ships on the planet, I hope we will also inspire the next generation with this work programme through to 2035.
"It isn't just good news for the Royal Navy, this is also good news for Scottish industry and Scottish taxpayers, this is an important step towards securing billions of pounds of investment in shipbuilding on the Clyde, securing hundreds of high-skilled jobs for at least the next two decades, and hundreds more in the supply chain across our country."
The construction of the new frigates, together with other vessels the Navy is committed to building, means that the UK will have a "formidable flotilla of firepower" by the 2020s, he added.
Scottish Secretary David Mundell, who toured the Govan yard with the Defence Secretary, said: "This is a great day for the Clyde, a great day for Scotland and a great day for our defence forces across the United Kingdom."
He added: "There is a lot of talk about uncertainty these days and I understand the impact uncertainty has on people's day to day lives, their families, and planning for the future, that's why it is so positive we can give this confirmation.
"We can give confirmation on the timing of the cutting of the steel, we can give confirmation in relation to the work programme going forward to 2035, and we can confirm across the United Kingdom that Scotland and here on the Clyde is the place to build ships.
"There is no doubt about the UK Government's commitment to the Clyde and this announcement completely shows that that is the case."
Plans to build the new frigates were set out in the Government's 2015 Strategic Defence and Security Review, although the project has been scaled back from earlier proposals to construct 13 ships.
But BAE Systems' managing director Nigel Whitehead said the work will be "a significant programme for the next two decades, manufacturing outstanding ships".
He said: "The timescale is very significant, just meeting the apprentices coming in makes me think there will be people who will work on this programme who have not yet been born - it's a long-term commitment.
"It's a vote of confidence in the capabilities of the company and the ability to deliver warships. It's good news for Scotland and the rest of the UK as well."
The Defence Secretary also announced MoD plans to sign a contract shortly to start building two Offshore Patrol Vessels (OPVs) by 2019, a move he said will protect jobs on the Clyde before the Type 26 programme gets fully under way.
Unite union regional co-ordinating officer Kenny Jordan said: "We're pleased that the Defence Secretary has finally committed to meeting the promises made to the workforce on the Clyde.
"Our members have been living with uncertainty for too long and this is a testament to the lobbying and campaigning that they have done over the last two years.
"This announcement secures the future of shipbuilding on the upper Clyde, supports skilled jobs in manufacturing and will provide opportunities for apprentices and trainees, making sure that we safeguard skills for the next generation."
Keith Brown, the Scottish Government's Economy and Veterans Secretary, said: "I welcome the news that the MoD has now finally confirmed its order for eight Type 26 frigates, to be built on the Clyde after much delay. This is a tribute to the skilled and dedicated workforces at Govan and Scotstoun.
"However, just as the workforce at the shipyard have faced considerable uncertainty we now face a continued wait for the response to the MoD's basing review in Scotland, which is considering sites like Fort George and Kinloss.
"The Scottish Government has written to the Defence Secretary asking him to meet us and discuss his plans for base cuts in Scotland. Despite promises, he has failed to do so.
"There has been no consultation with the Scottish Government - and I reiterate my call for the Defence Secretary to provide clarity as soon as possible."