Lawyers were today finalising a compensation bid on behalf of more than 4,000 customers allegedly left with rashes and burns after buying faulty sofas.
Solicitors Russell Jones and Walker said it was acting for customers who bought Pia and Bari sofas from retailers Land of Leather, Walmsley's Furnishing and Argos.
The firm said the rashes had been caused by the chemical dimethyl fumarate, a fungicide contained in a sachet, inserted to prevent mould during shipping.
"Crystals contained in these sachets transform into toxic gas, particularly when exposed to heat," said a spokesman for the solicitors. "This can then pass through clothes, causing the sofa rash."
Last year, the Honourable Mr Justice Treacy made a Group Litigation Order at Nottingham Crown Court which allowed people affected by the sofas to pursue compensation.
The spokesman said the action represented the UK's largest group litigation order for a consumer product.
He said the leather furniture at the centre of the claim was made by Chinese company Linkwise.
Legal experts estimated the pay-out could total several million pounds if the compensation bid was successful.
The spokesman said the case was being heard today at the Royal Courts of Justice, in London.
A spokeswoman for Argos said: "Over the last 18 months, there have been issues regarding certain sofas manufactured by a company based in China which were supplied to Argos and a number of other retailers.
"This issue is currently the subject of a group litigation order so we are unable to comment on any individual cases.
"Argos no longer sells the products."Reuse content