The UK's biggest wood-fired power station was today formally opened by the First Minister who hailed it as a green energy milestone.

The Steven's Croft "biomass" power station at Lockerbie will produce enough power to supply up to 70,000 homes, more than 17 times the population of the Border town.

The 44-megawatt station burns forestry left-overs and specially-grown willow, helping jobs and saving up to 140,000 tonnes a year of greenhouse gases.

Alex Salmond said the station marked a further step towards Scottish Government targets of 50% of electricity from renewables, and an 80% cut in carbon emissions by 2050.

"At a stroke, Steven's Croft more than doubles Scotland's biomass electricity generating capacity from 39 to 83 megawatts," said Mr Salmond.

"It is proof that not only can we generate power from materials previously seen as waste - we can create good quality jobs and improve the sustainable management of our forests."

He said the plant provided 40 jobs on site and would support 300 more in local forestry, sawmilling and agriculture.

"Scotland's renewable potential is immense - enough to meet our energy requirements many times over," said Mr Salmond.

"Biomass is a growing component of the mix."

The plant is owned and operated by E.ON UK.

It cost £90 million including a Lottery grant of £18 million, and most of its fuel comes from within a 60-mile radius.

David Mundell, Tory MP for for Dumfriesshire, Clydesdale and Tweeddale, and shadow Scots secretary, said: "It is great to see this area once again leading at the forefront of power technology - just as Chapelcross (nuclear plant) did 50 years ago.

"With the closure of Chapelcross, I am delighted that we still have energy production in the region and all the expertise that brings with it."

Liberal Democrats welcomed the opening but questioned the adminsitration's commitment.

Lib Dem MSP Jim Hume said: "I welcome the opening of the Steven's Croft plant, a project started by the previous Executive in 2006.

"I can't work up the same enthusiasm for the First Minister's comments about renewable energy.

"I am really disappointed that his Government has failed to take up Nicol Stephen's target of 100% of Scotland's electricity coming from renewable sources by 2050."