MUMBAI (Thomson Reuters Foundation) - A group of socially responsible investors has urged 160 major retailers who source clothes from Bangladesh to back the extension of an agreement which promotes the safety of millions of workers in garment factories in the South Asian nation.

The Bangladesh Investor Initiative, whose members are shareholders in several retailers, has asked the companies to support a three-year extension of a legally-binding accord to improve building and fire safety across the textile industry.

The Bangladesh Accord was signed by global brands and trade unions in 2013 after the Rana Plaza disaster, when about 1,100 people were killed after a garment factory complex collapsed - sparking outrage over poor working conditions in the sector.

Only 60 of the 220 companies in the Accord have signed an agreement to extend the program until 2021, says the network of institutional investors, which represents nearly 150 investors with collective assets valued at about $3.7 trillion.

The Accord has signatory clothing brands and retailers from about 20 countries, such as Britain’s supermarket group Tesco, Swedish fashion group H&M and German sportswear giant Adidas.

“It is critical to ensure that future safety problems are detected before they become life-threatening events,” Lauren Compere of Boston Common Asset Management said in a statement.

The appeal follows a $2.3 million settlement this week by a global clothing brand to meet fire and building safety regulations in 150 factories in its supply chain in Bangladesh.

Unions took the retailer, which cannot be named, to the Permanent Court of Arbitration in the Hague, arguing the company had not made it financially feasible for its factories to fix safety issues, endangering the lives of thousands of workers.

Bangladesh, which ranks behind only China as a supplier of clothes to Western countries, relies on the garment industry for more than 80 percent of its exports, and about 4 million jobs.

The Rana Plaza disaster, one of the world’s worst industrial accidents, prompted fashion retailers to work more closely together to protect workers in Bangladesh, and laws were introduced to ensure greater supply-chain transparency.

Yet campaigners say progress in fixing problems has been slow - with complaints from garment workers over low pay, poor safety standards and not being allowed to form trade unions.

“Continued solidarity is needed to finish the job and prevent hard-earned gains from disappearing,” said David Schilling of the Interfaith Center on Corporate Responsibility.