Labour is to call for an investigation into the blacklisting of workers by construction firms involved in major projects, including the Olympics and Crossrail.
The party said secret files on thousands of workers in the construction sector resulted in workers being denied employment after raising legitimate health and safety concerns or exercising their human right to belong to a trade union.
Unions have said that more than 40 of the UK's largest construction firms used a blacklist.
Many of the workers still have no idea that they were included on the blacklist which was uncovered by the Information Commissioner's Office (ICO) in a raid in 2009.
Labour said questions remain on why the ICO did not seize other documents found at the scene.
In a Commons debate next week, shadow business secretary Chuka Umunna will call for the Information Commissioner to adopt a proactive process for informing individual victims of blacklisting so that they can seek compensation.
Labour's motion asks the government to examine whether further changes are needed to ensure that effective sanctions are in place to tackle and prevent blacklisting.
Mr Umunna said: "Blacklisting is a national scandal. Workers have had their livelihoods destroyed, their reputations tarnished and in some cases their families torn apart just because they raised health and safety concerns or were a member of a trade union, and the further tragedy is that many of those affected have no idea that they have been blacklisted.
"As well as investigating blacklisting allegations in full, including those relating to public construction projects, ministers need to look again at what changes need to be made to ensure blacklisting is prevented and that this scandal is never repeated again."
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