Agency Workers Regulations
Under the Agency Workers Regulations, workers supplied by an agency become entitled to receive pay and basic working conditions equivalent to any directly employed employees after a 12 week qualifying period.
The rules came into effect on 1 October 2011 so the 12 week period commenced from 1 October 2011 for existing agency workers. Where these workers are still engaged by the hirer, they now qualify to receive pay and basic working conditions equivalent to directly employed employees.
Where an agency worker is at the entity for less than 12 weeks, a minimum break of more than six weeks between assignments with the same employer will be necessary for the rights not to be available.
For more details can be found here