The GMB and UCATT unions announced they have settled outstanding claims against Balfour Beatty, Carillion, Costain, Kier, Laing O’Rourke, Sir Robert McAlpine, Skanska and Vinci.

The case follows the discovery in 2009 of a blacklist of building workers held by the Consulting Association. It uncovered a list of more than 3,000 names and reference cards which detailed workers’ political views, competence, trade union membership and industrial relations activities.

In October last year, the contractors admitted that they defamed workers and infringed their rights.

The unions and law firm Guney, Clark and Ryan (GCR), acting for the Blacklist Support Group, announced they have accepted an apology.

A statement said: “The construction companies have offered financial settlements which all claimants represented by UCATT, GMB and GCR have now accepted as fair and reasonable.

“The parties have also agreed a joint statement to be read in court as part of this settlement. The construction companies have also agreed to pay the claimants’ legal costs.”

The firms involved said the announcement means they have settled the litigation between them and individuals represented by UCATT, the GMB and GCR regarding the activities of the Consulting Association, as well as the Economic League.

A statement said: “The construction companies have offered financial settlements which all claimants represented by UCATT, GMB and GCR have now accepted as fair and reasonable. The parties have also agreed a joint statement to be read in court as part of this settlement.

“These construction companies now wish to draw a line under this matter and continue to work together with the trade unions at national, regional and site level to ensure that the modern UK construction industry provides the highest standards of employment and HR practice for its workforce.”

There is outstanding litigation between the construction companies and the Unite union, with a trial due to start on May 9.