Shadow business secretary Chuka Umunna is calling on the culture secretary to answer allegations that Olympic contractors used blacklists on London 2012 construction projects, following a report in Construction News.
Umunna has put down Parliamentary Questions to Maria Miller urging her to investigate whether contractors spent public money to obtain information on construction workers from lists maintained by the controversial Consulting Association.
In a statement he said: "Allegations that blacklisting was used by contractors involved in the construction of Olympic Games are incredibly serious.
"Evidence from Ucatt suggests that blacklisting was used on an 'industrial scale' by construction firms in relation to public contracts."
The move came as RMT union leader Bob Crow spoke of his fears over a new blacklisting service, the website HR Blacklist, which lists profiles and pictures of British trade union activists, for employers to search.
A construction worker in front of the Olympic site
He said the site has echoes of the days of the Consulting Association, which held a secret blacklist of 3,200 construction workers who were active union members.
Four years ago, the Information Commissioner's Office found the Consulting Association's database, and discovered major firms like Balfour Beatty, Costain and Skanska Construction had used the blacklist to identify potential troublemakers - with information on their families, their attendance at union meetings and demonstrations.
But could the blacklist have been used by companies building Olympic sites?
Construction union Ucatt have demanded a public inquiry into the possibility.
Umunna said: "Allegations that blacklisting was used by contractors involved in the construction of Olympic Games are incredibly serious.
"I have put down Parliamentary Questions demanding that the Culture Secretary investigates this matter fully. As a matter of urgency we need to get to the bottom of what happened."
Ucatt general secretary Steve Murphy told the Scottish Affairs select committee this week that he believed Sir Robert McAlpine had undertaken a "surge in blacklisting checks" as it recruited workers for the Olympics, and spoke of fears that taxpayers money had been used to pay for access to blacklists.
The Consulting Association, before it was shut down in 2009, reportedly had an increase in income around the time that construction workers were recruited for the Olympic sites - but it has not been proven that the income increase has any link whatsoever to Olympic recruitment.
In July, blacklisted workers launched a High Court claim against Sir Robert McAlpine estimated to be worth at least £17 million.