Council bosses have admitted that they are working with a company that once used a “blacklist” to vet workers who were trade union members — despite making a public pledge never to employ such firms.

Construction and property group Kier was issued an enforcement notice by the Information Commissioner’s Office (ICO) in 2009 after being found to have used the Consulting Association, which created and managed the blacklist.

The group recently took over construction firm May Gurney, which has a vehicle maintenance contract with Barking and Dagenham.

Fresh calls for an investigation into blacklisting allegations have been made by unions and politicians concerning the £14.5bn Crossrail project in London, which Kier is involved in as part of consortium BFK with two other companies.

In May this year, council leader Cllr Liam Smith told a full council assembly meeting that the authority would never employ firms involved in blacklisting.

He said: “Blacklisting of trade union members is abhorrent.”

Co-founder of the Blacklist Support Group, Dave Smith, said he set up the organisation after learning he was a victim.

“What I don’t want is the same thing happening to other people in Barking and Dagenham. There are questions that need to be asked of Kier.”

The Consulting Association’s blacklist was subscribed to by more than 40 construction firms. Company boss Ian Kerr was fined £5,000 in 2009 for breaching the Data Protection Act after an ICO investigation.

A Kier spokesman pointed out the association is now disbanded and referred to its activities as “historic and clearly regrettable”.

He said Kier does not condone any form of blacklisting and added: “Kier co-operated fully with the investigation by the Information Commissioner’s Office in 2009.

“Having concluded its investigation and issued Kier Ltd, as well as 13 other construction companies, with an enforcement notice, the ICO has taken no further action against Kier in respect of the matter.”

A Barking and Dagenham Council spokesman repeated Cllr Smith’s condemnation of blacklisting but said the council cannot prevent the sale of May Gurney to Kier and confirmed the contract will not be re-tendered.