Anti-blacklisting guidelines published by Scottish government
The Scottish government has published guidelines to stop the blacklisting of workers involved in public contracts.
The new rules mean companies bidding for work must disclose whether they have been involved in the illegal practice, and if so, they must show that "remedial action" has been taken.
In future, companies found to have breached laws against blacklisting could have their contracts terminated.
First Minister Alex Salmond warned that the practice would "not be tolerated".
The Scottish Trades Union Congress (STUC), which contributed to the guidelines, has welcomed the move, which coincides with a UK-wide 'day of action' against blacklisting.
Blacklisting is the term used to describe the practice of firms using, compiling, selling or supplying details of people who are or have been union members, in order to discriminate against them.
Unions and MPs have called for a public inquiry after it was disclosed that a database of 3,000 names had been used to vet workers in the construction sector for more than 15 years.
A raid on The Consulting Association by the Information Commissioner's Office in England in 2009 revealed that construction firms had been checking potential employees against a blacklist.
Workers on big public projects such as the London 2012 Olympics and Crossrail were found to have been blacklisted, though many were not aware that information had been collated and used against them.
Earlier this year, a report by the Scottish Affairs Committee at Westminster said it was "appalled" at the extent of the practice and said many of the biggest names in construction had been involved.
Suppliers hoping to win public contracts in Scotland will now have to complete a questionnaire, which requires them to disclose whether they have previously breached laws against blacklisting.
If found to have used a blacklist, the bidder will have to show it has taken remedial action, including apologising to affected workers, issuing a statement on future conduct and proving compliance with any tribunal ruling made against them in relation to the practice.
Meanwhile, a new contract clause, to be included in the standard terms and conditions for bidders, allows for contracts to be terminated if a supplier has broken the law.
The guidelines are likely to be made statutory as part of the Procurement Reform Bill currently going through the Scottish Parliament.
Mr Salmond said: "The Scottish government is opposed to blacklisting in any form, given the serious impact it can have on the career, livelihoods and lives of those affected.
"Everyone has a right to work and to raise concerns, including through a union.
"We are making it absolutely clear to any company wishing to tender to supply, build or service parts of our national infrastructure, or to deliver our public goods and services, that blacklisting will not be tolerated and that they face being excluded from bidding for public contracts if found to be taking part in this unacceptable practice."
STUC General Secretary Grahame Smith said it would continue to work with the Scottish government "to monitor the use of this guidance and provide further evidence where we believe the practice of blacklisting continues."
Labour MSP Neil Findlay welcomed the new guidelines but said more action was need as blacklisting was still going on.
He added: "We need those companies which have been involved in blacklisting to accept what they've done was wrong, fully compensate the thousands of workers who have been denied work for many years, and to change their practices.
"We know that blacklisting is still going on in different industries. This must stop."