Computer generated image of what the new Successor submarine will look like ahead of the renewal of Britain's Trident nuclear deterrent
Hulls of the new £31 billion Trident submarines will be built with steel provided by a FRENCH firm.
BAe Systems, building the subs in Barrow-in-Furness, Cumbria, opted for a French supplier after signing a contract with the UK government.
The deal, which The Mirror reports will be worth tens of millions, came after a plan between two British firms to make a joint bid for the work flopped.
The UK Defence Secretary announced work on the new nuclear deterrent will begin today as the first pictures of £31billion Trident submarines were unveiled.
Sir Michael Fallon said he will officially mark the start of construction work on the Successor submarines that carry the controversial Trident missiles later today.
Renewal of the continuous-at-sea deterrent is predicted to cost £31 billion, with a £10 billion contingency fund also set aside.
Speaking at the Conservative Party Conference in Birmingham, Sir Michael told delegates: 'Tomorrow I will go from here to Barrow to cut steel on the first new Successor Trident submarine - a billion pound investment programme that will benefit businesses from Barrow to Berkshire, from the north of Scotland to Tyneside.
'And what a contrast with the Labour Party - while we're getting on with the Successor programme, they can't even agree on a successor to Jeremy Corbyn.'
Roy Rickhuss of steelworkers' union Community said: 'The Defence Secretary is boasting about cutting steel while in reality these submarines have snubbed British-made steel. This is a betrayal of British workers.'
Trident provided one of the main bust-ups at last week's Labour conference, when shadow defence secretary Clive Lewis's speech was rewritten to remove a statement that Labour would not ditch its policy of supporting renewal.
Aides later confirmed that Mr Corbyn remains personally committed to unilateral disarmament.
For Labour, Mr Lewis said: 'Michael Fallon's speech was a smokescreen, designed to deflect from the Tories legacy of failure on defence.
'The reality is their devastating cuts since 2010 have weakened and demoralised our armed forces, leaving them poorly-equipped, over-stretched, under-paid and too often living in squalid conditions.
'The Tory obsession with cost-cutting means they are not even using British steel to build our ships and vehicles.'
Sir Michael has also pledged 'more homes for heroes' by extending a scheme which allows troops and military workers to get on the property ladder.
He said the Help to Buy scheme for service personnel will run until 2018, with thousands of applications approved since a three-year pilot project started in 2014.
The Ministry of Defence (MOD) says more than £127 million has been paid to around 8,300 military personnel so far, adding the total of approved applications stands at 10,584.
The Cabinet minister also claimed the armed forces can be a 'remarkable engine of social mobility' as he reiterated his desire for 50,000 military apprenticeships from 2015 to 2020, and 150 new cadet units in state schools.
He pointed to Rockwood Academy in Birmingham - formerly known as Park View - as being among the first 25 schools to have new cadet forces, noting it was at the centre of anonymous allegations which claimed there was a plot by Muslim hard-liners to take control of several of the city's schools.
During his conference speech, he said: 'Last year I told you I wanted our forces' Help to Buy scheme to help 10,000 personnel and we're meeting that target.
'But I want more of our servicemen and women to have the chance to buy their own homes so I am extending the scheme through until 2018 - more homes for heroes.
'And we aren't just helping servicemen and women get on the housing ladder, we are selling Ministry of Defence land we don't need to build the homes we do.'
Earlier, Sir Michael said of the cadet scheme and Rockwood Academy: 'This used to be a 'Trojan Horse' school.
'It has been turned around completely and instead of promoting religious segregation, today, as a new academy, it is instilling British values with a school cadet unit that will parade this afternoon, serving the Queen and country.'
Vanguard submarines, that have been carrying Trident nuclear missiles since 1993. dailymail.co.uk
Britain has a fleet of four Vanguard-class vehicles, pictured, with at least one on patrol at all times carrying 16 warheads. dailymail.co.uk
VANGUARD SUBMARINES: AT A GLANCE
Weight: 15,900 tonnes
Engine: One Rolls Royce PWR2 nuclear reactor, two electric turbines, one pump jet propulsor, two turbo generators, two diesel alternators
Speed: 29mph (submerged)
Arms: 16 Trident missiles, four torpedo tubes
Cost: £1.5billion each