A union leader has described the blacklisting of construction workers as a "national scandal" as a study showed 69 workers in Tyne and Wear have been affected by the issue.
Len McCluskey welcomed a Commons debate on blacklisting and said there should be a Leveson-style inquiry into the "scandal".
Legal action is being taken on behalf of a number of construction workers, who are seeking compensation for having their names on the blacklist.
Labour will call for an investigation into allegations that firms involved in major construction projects, including the Olympics, blacklisted workers.
The party said secret files on thousands of workers in the sector resulted in them being denied employment after raising health and safety concerns or exercising their human right to belong to a union.
Unions have said that more than 40 of the UK's largest construction firms used a blacklist.