Workers earn no more on tea estates certified by Fairtrade International, Rainforest Alliance and UTZ Certified than on non-certified estates, new research has found.

The report into low wages in the tea industry – published by Oxfam and the Ethical Tea Partnership – found that certification was failing to make any difference to wages because it focused only on whether wages met minimum legal requirements.

Fairtrade claimed it had limited power to raise sector wages, as they are often negotiated at country or regional level.

The Oxfam report agreed this practice was a key factor preventing wages from rising, and acknowledged certification schemes brought other benefits to workers. “Certification is an important tool which has helped improve the livelihoods of smallholder producers across the globe and brings a range of benefits to workers which are not explored in the report,” Oxfam said.

It also said regional government policies to maximise rural employment were locking workers into low pay agreements by overburdening plantations with excess workers.

Fairtrade International, Rainforest Alliance and UTZ Certified have agreed to strengthen their standards in relation to pay. For example, Fairtrade said it would revise its Fairtrade Hired Labour Standards and give guidance on ways to make progress towards a living wage for tea workers.

The news comes after The Grocer reported last week that tea plantation owners were turning against Fairtrade.

Williamson Tea – one of the first major tea farmers to go Fairtrade in 2006 – has withdrawn its support for Fairtrade Foundation. The plantation owner said it was forced to sever ties because the operations and personnel of Fairtrade “threatened the integrity of our commercial operations”.

Another tea grower said high fees and onerous paperwork had made it difficult to maintain support for Fairtrade.