THE blacklisting of workers on Europe's largest construction project is "organised and systematic", MPs have been told.

Appearing before the House of Commons Scottish Affairs Committee, which is conducting an inquiry into blacklisting, Gail Cartmail, assistant general secretary of Unite, said the evidence it was happening on London's Crossrail scheme was circumstantial but people could "join up the dots."

Crossrail denies workers have been blacklisted for raising safety concerns on the £150 billion project and has pledged to act on any substantive evidence.

However, Ms Cartmail branded the Crossrail consortium and contractor BFK as "congenitally uncurious" about claims of blacklisting.

In written evidence to the committee, Unite claimed the vetting process was "designed to find and prevent union activists from being hired". The trade union said the construction industry had been tainted by blacklisting for decades but that it gained prominence in 2009 following an official raid on the Consulting Association, a body which "maintained a blacklist of workers used by large construction companies".

Despite the association being closed down, Unite insisted a "pattern of unethical behaviour in the construction industry" continued.

A consortium spokesman pointed out all contractors have to comply with the law, which bans blacklisting.