HARRIET Harman, Leader of the Commons, yesterday pledged to end the "scurrilous activity" of blacklisting.
She said the government was "totally opposed" to blacklists and aimed to ensure there was "effective enforcement".
Last week, an investigation by the Information Commissioner found major construction firms broke data protection laws by paying for
information on their employees.
Information on about 3,000 workers was held by the Consulting Association in paper files and a card index database, according to the commissioner.
Notes about individual workers included descriptions such as "ex-shop steward, definite problems", "Irish ex-army, bad egg", while others related to workers who had raised concerns over health and safety issues on sites.
In the Commons yesterday, Labour's Michael Clapham urged the government to make it an offence to compile or commission a blacklist. His Commons motion on the subject has so far been signed by 70 MPs.
Mr Clapham asked Ms Harman to raise the issue with Jack Straw, the Justice Secretary.
Ms Harman said: "I don't think a trade union health and safety representative should find they are on a blacklist and will never be able to work again. We are totally opposed to that and want to make sure there is most effective enforcement of it."
