MPs have called on the Business Secretary Vince Cable to agree a full-scale investigation into blacklisting in the construction industry, following allegations by the Unite union.
The MPs they have received "clear proof" from Unite of the blacklisting of trade union members working on the Crossrail contract.
The Commons' Scottish affairs committee said evidence from Unite suggested employees claims worried by issues such as health and safety and their employment rights required has been blacklisted and the claims should be investigated rapidly.
The Trades Union Congress (TUC) General Secretary Frances O'Grady said: "Over the years thousands of workers have suffered the injustice of being denied work simply for raising concerns about the safety of their colleagues.
"Blacklisting is a shameful practice that has no place in a modern economy. It causes misery for those on the blacklist and puts at risk many thousands of construction workers who feel unable to raise safety concerns, in one of the country's most dangerous industries, for fear of losing their livelihoods."
She concluded: "It's not enough for the government to refer the issue to the Information Commissioner. The Business Secretary must carry out a proper investigation into blacklisting to stamp out this abuse for once and for all."