The Clyde's last commercial shipyard has won a £97m contract to build two ferries, securing 150 jobs for two and a half years.

Ferguson Marine in Port Glasgow, saved from closure by billionaire businessman Jim McColl, will make both vessels for Calmac by 2018.

The contract is a huge - although widely expected - boost for Mr McColl's long-standing ambitions to build bigger ships at the yard. He aims to build the first ocean-going commercial ships in years - and is eyeing an expansion in to Greenock's nearby Inchgreen drydock.

The two new ships will be 100m long and capable of carrying up to 16 trucks or more than 100 cars as well as up to 1000 passengers.

That means they are likely to be heavy-duty workhorses on on core CalMac routes to key destinations like Arran and the Western Isles.

Crucially, the ships will be able to use eco-friendly liquid natural gas as well as traditional marine diesel. That will make them the kind of the state-of-the-art duel-fuel vessels plying many routes in northern Europe.

Ferguson was announced as preferred bidder for the ferries in August and negotiations have now been completed. The Scottish Government, which owns CalMac, formally awarded the contracts.

Ferguson Marine’s managing director, Liam Campbell, said: "This is a great achievement for the yard and great news for the local community. "The signing of the shipbuilding contracts today marks the beginning of a new era of commercial shipbuilding on the Clyde and in conjunction with our experience in building battery hybrid vessels, confirms Ferguson Marine Engineering as a lead designer and builder of innovative green vessels internationally."

Derek Mackay, Minister for Transport and Islands, said: “I’m delighted this contract has been formally awarded to Ferguson Marine Engineering Limited (FMEL) and the shipyard can now start work on these new ferries, the largest commercial vessels to be built on the Clyde since 2001.

"The award of this contract will see FMEL’s 150-strong workforce retained and more staff taken on, underlining the Scottish Government’s commitment to creating the vital jobs needed to boost local economies and help stimulate growth across Scotland.

"I once again congratulate FMEL on proving Scottish shipbuilding can succeed in a competitive market, and I look forward to seeing these new vessels join the West Coast ferry fleet in the future.”

Tom Docherty, chief executive of Caledonian Maritime Assets Ltd, which owns the state ferry company's vessels, said: "Key items of equipment will now be ordered, detailed plans will be developed for approval and it is anticipated that actual construction will start early in 2016.

"We hope to see the first of these vessels in operation in early 2018.”

Mr McColl, acquired Ferguson Marine in September last year and immediately stated his intention to expand the business and create new jobs. The CalMac ferries deal could see 400 people employed at the yard.

Mr McColl previously said he hoped to have as many as 1400 workers in five years.