H&M and Marks & Spencer have been condemned for sustaining "abject poverty".
A new report from Labour Behind The Label alleges the retailers have not lived up to claims around ethical labour practices.
It comes as H&M and M&S both pursue Australian expansion strategies.
The report Do We Buy It? analysed plans to introduce living wages to offshore workers.
"Although a lot of noise has been made by both H&M and M&S about their intention to improve wages, there has been little sign that this is actually making a difference to workers," the report claimed.
The report claims that workers at M&S suppliers in India, Sri Lanka and Bangladesh continue to live in abject poverty.
Despite efforts, it alleged workers share slum housing and often working illegal levels of overtime – up to 110 hours a month over contracted hours.
Some 60% of workers interviewed were struggling with mounting debt just to meet their basic needs.
In Sri Lanka workers interviewed were paid an average of £3.23 a day, including overtime (a ten hour day).
In months with high production quotas workers would be made to work 100 hours overtime a month, twelve hour days, 40 hours over the legal limit.
Often workers lived in small rooms, 3x3m, shared by two or more workers. 75% of workers did not have running water or access to a tap, and most were sharing an outside toilet with 10 or more others.
In India workers reported food and education expenses were difficult to meet on their wages, with one worker stating: “Our income is not enough. We don’t buy eggs, meat, fish or fruits because of high costs."
The report's investigation into H&M’s living wage promise was less conclusive.
Labour Behind The Label sought out H&M strategic suppliers in Cambodia to analyse their wage levels.
The report alleged wages had increased, but not enough to meet a living wage level.
In some factories, piece rate systems had been put in place causing workers to skip breaks, and leaving them exhausted and prone to regular illness.
Average take home pay came in at $187.97 a month (£123.71) but workers estimated they needed $230 a month to live with dignity.