Agency staff are being switched from their normal duties to work undertaken by employees on strike to get round the legislation, according to Thompsons, the UK’s largest firm of trade union and employment rights lawyers.

Thompsons urges the Government to make it crystal clear that under Regulation 7 of the Conduct of Employment Agencies and Employment Businesses Regulations 2003, agency staff originally supplied for other purposes should not be used to perform the duties of strikers. At the moment some businesses are subverting the intention of the regulation.

Thompsons believes there should be a duty on any employer to inform an employment agency if the workers it supplies may be used to perform the duties of strikers.

There should also be a fast-track procedure for investigating complaints by unions. At the moment unions are invariably unable to seek redress during industrial action because of the time taken to conduct inquires.

Richard Arthur of Thompsons said: “It can take months to conduct an official investigation into complaints. By then the damage - as far as unions are concerned - has been done.

“We have found by using the Freedom of Information Act that there has been no prosecution under regulation 7 since the legislation came into force in April 2004. That fact speaks for itself.”

Read Thompsons Solicitors' full response on The Conduct of Employment Agencies and Employment Businesses Regulations 2003.