MORE than 500 Scottish construction workers were blacklisted for jobs because of union activity and could now be eligible for compensation.

The Scottish Affairs Select Committee launched an inquiry after files containing personal details about 3213 workers were discovered at a Worcestershire-based firm called The Consulting Association (TCA).

The files were used by more than 40 firms including Balfour Beatty, Sir Robert McAlpine, Laing O'Rourke and Costain to check the backgrounds of potential workers.

The Sunday Herald revealed the effect of the blacklisting on Scottish workers back in October 2012, but the number of Scots affected by the scandal was not known.

Information obtained by the Sunday Herald now shows at least 520 people from Scotland were vetted for jobs but only 50 have been made aware they were victims.

The Scottish workers had files kept detailing their personal relationships, trades union involvement and employment history,

On the list are 142 workers from Glasgow, Clydebank and Dumbarton, 53 from Ayrshire, 51 from Edinburgh, and 28 from Aberdeen. Others are from all over Scotland.

Last Wednesday David Cameron told MPs the blacklisting was "a completely unacceptable practice".

In a Labour-led debate on the issue, Labour's Michael Meacher described blacklisting as the "worst human rights breach in the UK since the war".

A group of 86 workers have launched a High Court action against construction firm Sir Robert McAlpine for compensation as a result of the firm's alleged central role in creating The Consulting Association. The bill for compensation could total £600 million.

Ian Kerr, a former consultant, was prosecuted in 2009 for putting together the blacklists of construction workers. Kerr died last year, just after giving evidence to the inquiry.

In an interview before his death, Kerr claimed the association had links with police and security services.

He described a meeting organised by the association in 2008 when eight construction industry directors were addressed by a "key officer" from the National Extremism Tactical Co-ordination Unit (Netcu), a Huntingdon-based police organisation set up to counter "extremist" protest groups.

Kerr said that codes were used to indicate those who were of interest to Special Branch — "Irish ex-Army, bad egg" was one example of this.

Pressure is now growing on the Information Commissioner to contact all of those affected, who could be in line for thousands of pounds in compensation for years of lost wages. Cases are being prepared.

Justin Bowden, GMB national officer, said: "They have been the victims of injustice over many years by multinational companies now seeking to live off public-sector contracts.

"When in 2009, the Information Commissioner's Office (ICO) seized a Consulting Association database of 3213 construction workers they never contacted anyone on the list to let them know they were blacklisted.

"By autumn 2012 only 194 of the 3213 people on the blacklist knew ... GMB priority now is to step up the campaign to get each and every GMB member blacklisted proper compensation.

"GMB is also still pushing ICO for a proactive action to inform all builders on the list that they are on the blacklist."