Sir Michael Fallon has insisted that no other industry in Britain enjoys as much certainty about its future as shipbuilding on the Clyde, as he countered union concerns over future Royal Navy orders.
With work on a new Type 31e frigate to be opened to bids, Unite said it was "not sure" it could trust UK Government promises on future orders.
Duncan McPhee, a senior shop steward, said he believed the work should be coming to Glasgow, along with the eight Type 26 warships and three offshore patrol vessels currently under construction.
But changes to the UK Government’s tendering process will see the next generation of light frigates built at yards around the UK. The Scottish Government last month accused the Ministry of Defence of reneging on a promise to build them on the Clyde.
Bur Sir Michael insisted during a visit to the BAE Systems yards that he had “kept faith” with Scotland’s shipbuilding industry.
He said: “The Clyde is turning out frigates. I cut steel on the first one back in July, HMS Glasgow. There will be seven other heavy frigates, that’s 20 years worth of work.
“There is no other industry in Britain that has such certainty, 20 years worth of work for the Clyde, guaranteed.”
BAE is planning a partnership with rival Cammell Laird which could see the next batch of frigates constructed on Merseyside while the Scottish yards work on their design and combat management systems.
Sir Michael said he expected a powerful bid from them, but added that there would be other bidders. He also said during the visit that he was happy to talk to the unions about their concerns.
The Defence Secretary was visiting the BAE Systems Scotstoun yard in Glasgow, where his wife Wendy named the new offshore patrol vessel, HMS Medway. He also travelled to the Ferguson shipyard in Port Glasgow.
Speaking earlier on the BBC’s Good Morning Scotland programme, Mr McPhee claimed competition between yards for Navy contracts was dangerous, had been tried in the 1980s and led to some going out of business.
He added: “This work should have been concentrated in Glasgow. It should have been 13 frigates. Now it is down to eight.
"The government is trying to introduce a failed policy for complex naval ships, which is to have open competition within a country.
"None of our peer countries do that - France, Italy, Spain, Germany, certainly the US. They have what is called a national champion to provide complex naval ships. We had this failed policy in the past.
"If we go back to the 1980s, we had internal competition where shipyards went bust taking on contracts that they couldn't deliver.”
He said the union supported spreading work across the UK on larger vessels, like the two new aircraft carriers, but not on smaller ships like the new frigate.
He added: "That doesn't apply to the Type 31 contract. It is only a small ship, so the block-build part across the UK will not happen because it would be absolutely uneconomic.”