Workers’ leaders in the construction industry have today called for an investigation into blacklisting on the 2012 Olympics site after revelations about the practice were raised at the London Assembly this week and previously in Parliament.

The Assembly voted on Wednesday to declare that any blacklisting of workers who raise health and safety concerns won’t be tolerated.

The Ucatt union revealed the link between blacklisting and the Olympics when it gave evidence to a Parliamentary committee in November.

Contractors admitted the practice of checking applicants’ backgrounds during recruiting. A secret list of workers to be barred from the industry was being used in 2007 by the Consulting Association, which was later closed down by the Information Commissioner.

The Association’s former head, Ian Kerr, told the Scottish Affairs Select committee under oath that blacklisting had been carried out by at least two contractors, the union pointed out.

Union general secretary Steve Murphy said today: “We need a full investigation into the true level of blacklisting to find out who was involved and who knew about it.

“Blacklisted workers deserve the truth and they deserve justice.”

The London Assembly on Wednesday called on the Mayor to show what steps have been taken to make sure the practice is not being used on the £15 billion Crossrail project.

Its resolution stated: “Every employee must be protected in raising health and safety concerns without fear of reprisals.”

The London Legacy Development Corporation’s chief executive Dennis Hone has partially addressed concerns about blacklisting on the Olympics site, the Assembly heard. The resolution mentioned his ‘regret’ about the issue being raised after the project was completed.

The union has asked the Development Corporation to investigate blacklisting, but says it has repeatedly denied the practice.

It has accused the corporation’s chief of “seeing no evil and speaking no evil.”