The project to reopen a rail line between Edinburgh and the Scottish Borders has officially started.

Transport Minister Stewart Stevenson said the railway could be a catalyst for economic growth right across the south of Scotland.

Lib Dem MSP Jeremy Purvis said it was a "positive move" but hoped construction work could be speeded up.

Mr Stevenson was in the Borders to formally activate the Waverley Rail Act - the bill which means the link must be built.

He said the action made clear the Scottish government's commitment to the scheme saying "when finished, the railway will act as a catalyst for economic growth right across southern Scotland, supporting hundreds of jobs during its construction," he said.

"It will also increase business development and housing opportunities across the region, whilst helping promote inward investment."

He said that as well as the economic benefits it would open up south east Scotland to rail passengers for the first time in more than 40 years.

The activation of the Waverley Railway Act commits the government to construct the whole of the railway from Edinburgh to Tweedbank.

Scottish Borders Council leader David Parker said he was "absolutely delighted" with the progress being made.

"Today's announcement is the most significant step forward and everyone can now look forward with confidence to the railway's delivery," he said.

"The triggering of the bill is a significant commitment by the Scottish government to this project and there can be no doubt that today represents the beginning of the actual physical delivery of the line.

The project will consist of 35 miles of track, 10 stops and seven new stations.

At a projected cost of £235 - £295m, supporters say it will provide a business boost to the area but opponents do not believe it makes economic sense.

The current target for completion is 2014.