Agency and temporary workers are set to receive the same rights to base pay and holiday entitlement as permanent staff under new legislation. The prime minister has unveiled plans for legislation in the next parliamentary session that will "ensure new rules for fair treatment of agency workers".

The announcement is a u-turn by the government, which has, for years, resisted pressure from unions and the European Union to back the Agency Workers Directive. It follows extensive media coverage of a private member's bill on the issue.

Agency and temporary workers placed in an organisation are to be given rights to the same terms and conditions as the firm's permanent employees in relation to base pay and holiday entitlement.

Although employers will be expected to provide a similar employment package for these workers as for their permanent staff, individual benefits, such as pensions and sick pay, are excluded.

The government plans to give agency and temporary workers the same rights as full-time employees after 12 weeks' service with an organisation.

But Mark Hammerton, employment law partner at Eversheds, said: "Many agency staff work for agencies because they like the flexibility that this brings and some of them might be unhappy about losing some of this flexibility under the proposed legislation."

Although the new legislation is expected to be announced in the Queen's speech this autumn, Hammerton suggests it could be as late as 2011 before it comes into effect.