The Union of Construction, Allied Trades and Technicans (UCATT) is concerned about the new Construction Industry Scheme (CIS), which streamlines the registration process for contractors and allows them to register online.

That means construction workers won't have to carry a card with their photograph on it, and only a limited number of applicants will be asked to attend the tax office to verify that they are who they claim to be. The new scheme takes effect from 6 April.

HM Revenue and Customs (HMRC), which administers the scheme, told The Independent that it was up to employers to ensure contractors were legitimately self-employed, and said the card was to ensure people paid their tax, not an identification scheme.