Supermarket Asda and the Unite union have struck a deal that means thousands of temporary workers in the food industry will win pay equal to that of permanent staff.
Now Asda wants others to follow and make suppliers pay agency workers the same rate as permanent employees, according to The Times.
The move effectively fires the starting gun on the Agency Workers Directive more than a year before it is set to be introduced officially.
Around 6000 workers from 29 suppliers are expected to benefit from improved pay under the Asda deal.
The Recruitment and Employment Confederation (REC) said it was "disappointed" at the lack of consultation.
Head of public policy Anne Fairweather said: "Agency workers play a valuable role in ensuring that meat and poultry is prepared and ready for sale in a fluctuating market place.
"The REC fully supports that these workers are recognised and duly rewarded for their work, but it is the responsibility of supermarkets, such as ASDA, to ensure that there is enough money in the supply chain if equal treatment in terms of pay, is to be reached.
"The REC is disappointed that the investigation by ASDA and Unite has taken place without the consultation of bodies that represent agencies in the supply chain, such as the Recruitment and Employment Confederation.
"We would encourage them to consult and involve all parties moving forward, to ensure that their proposals are workable in practice."