After more than 1,100 deaths[1] exposed dangerous labor conditions in Bangladesh in 2013, brands like H&M, Walmart[2] and Gap[3] were among the most powerful companies that pledged to improve the safety of some of the country's poorest workers.

But human rights groups say that three years later, those promises are still unfulfilled, and that safety, labor and other issues persist in Bangladesh and other countries where global retailers benefit from an inexpensive work force.

A series of new reports by the Asia Floor Wage Alliance, a coalition of trade unions and other research and advocacy groups, has put a new spotlight on the conditions. In Bangladesh, the group says, tens of thousands of workers sew garments in buildings without proper fire exits. In Indonesia, India and elsewhere, pregnant women are vulnerable to reduced wages and discrimination. In Cambodia, workers who protested for an extra $20 a month were shot and killed.

The brands say that in recent years they have aggressively pushed stronger labor protections and vastly increased their monitoring of the factories that make their products. They have also made significant structural and fire repairs at many factories in Bangladesh.

But even the retail groups say that more improvement is needed, a message underscored in the new reports. Worker advocates say that progress on improving conditions at the factories has been too slow, and that some of the world's biggest companies continue to benefit from unfair and dangerous labor practices.

"There have been substantial safety renovations in factories that have unquestionably made those factories substantially safer," Scott Nova, the executive director of the labor monitoring group Worker Rights Consortium, said of the work in Bangladesh. "At the same time, it's also true that there have been unacceptable delays."

On Tuesday, the Wage Alliance released its latest report[4], which accuses Walmart of benefiting from forced labor and other abusive practices in a number of Asian countries. In Cambodia, for instance, workers at factories who make products sold at the company are required to work 10 to 14 hours a day in sweltering heat, without access to clean drinking water or breaks — conditions that have contributed to "mass fainting episodes," the report said.

Workers who refuse or who try to speak up for themselves risk being fired, according to the report.

In a statement, Walmart said that its standards for suppliers "specifically address working hours, breaks, the cultivation of a safe and healthy work environment, and freedom of association." The retailer said that it does not own or operate facilities in Cambodia or Bangladesh, but that it expects suppliers to "uphold these standards in the factories from which they manufacture products."

The Wage Alliance is releasing its studies to coincide with the International Labour Conference in Geneva that began Monday.

This month, the group released a report[5] that detailed sexual harassment, low wages and other abuses at H&M's supplier factories. Anannya Bhattacharjee, the international coordinator for the Wage Alliance, also said that dangers persist at factories in Bangladesh, where the more than 1,100 workers died in the Rana Plaza collapse, one of the deadliest industrial disasters in history.

"At this point, we do not see H&M working in a way that would prevent another Rana Plaza," Ms. Bhattacharjee said.

In a statement, H&M characterized the challenges outlined in the report as "industrywide."

"The report raises important issues, and we are dedicated to contributing to positive long-term development for the people working in the textile industry within our sourcing markets," the company said. "H&M has been working actively for many years to help strengthen the textile workers' conditions and will continue to do so."

Factories in many developing countries are under enormous pressure to churn out billions of dollars worth of goods at costs low enough to beat out the competition for business from foreign companies.

H&M, with $25 billion in sales last year, is one of the biggest beneficiaries of the so-called fast-fashion craze, relying on factories in many countries to help quickly refresh its clothing offerings. Walmart, the largest retailer in the United States, has created an huge business out of inexpensive goods.

But the collapse at Rana Plaza renewed discussions about how the appetite for cheap products affects some of the world's most vulnerable workers. What costs must be cut, for example, in order to sell a T-shirt in the United States for $5?

After Rana Plaza, two coalitions of retailers — one dominated by European brands, the other American — each made a five-year commitment to regular inspections, repairs and other corrective measures aimed at improving working conditions in Bangladesh.

The Accord on Fire and Building Safety in Bangladesh, led by the Swedish retailer H&M, was largely seen as stronger because it included a legally binding arbitration provision to resolve labor disputes. The other group, the Alliance for Bangladesh Worker Safety, which includes Gap and Walmart, has no such clause, but it can impose financial penalties and expel members who violate its terms.

Both groups say they have made progress. Of the 108,000 issues identified through inspections at the roughly 1,600 factories covered by the Accord, 60 percent have been reported or confirmed as corrected, according to a spokesman, Joris Oldenziel.

The Alliance group has repaired more than half of the issues at more than 600 active factories, according to its website[6]. That has made its factories "considerably safer," said James F. Moriarty, the country director for the Alliance.

But both of the retail coalitions admit that progress has been slow: Nearly 1,400 corrective action plans are behind schedule at factories covered by the Accord, according to its website[7]. Political unrest and a lack of qualified engineers had contributed to delays, Mr. Moriarty said.

One widespread issue: fire safety. Fire doors, which can withstand high temperatures for a set period of time, are not common in Bangladesh and need to be imported, the Alliance group said. The doors isolate a fire and keep flame and smoke out of stairwells. The Rana Plaza collapse happened just a few months after the Tazreen Fashions fire, which killed 112 Bangladeshi workers.

As of 2015, nearly 79,000 workers continued to produce garments for H&M in Bangladesh in buildings without proper fire exits, according to the Wage Alliance.

"It's so grossly irresponsible to put thousands of workers into a building that doesn't have them," Mr. Nova said.

A building's safety is just one of the issues that human rights and labor advocates say must be addressed in Bangladesh and elsewhere.

The Floor Wage Alliance's report[8] on Gap, for instance, pointed to "sweatshop" conditions at one of the retailer's suppliers: Workers in one factory were regularly forced into working more than 100 hours a week at poverty-level wages.

In a statement, Laura Wilkinson, a spokeswoman for Gap, said that the company worked with a "wide-range of stakeholders," including workers, unions, governments and nongovernmental organizations, to improve conditions at the factories that make its clothes.

She pointed to the company's Code of Vendor Conduct, which requires workers to be paid either a legal minimum wage or a wage that meets local industry standards. The code also said that factories are "encouraged" to pay enough so that workers can cover their basic needs and have some discretionary income. Gap says it has about 70 local staff members who help enforce its standards in the countries that make its products.

The commitments from the Alliance and the Accord group are set to expire in 2018. Labor advocates are skeptical that companies like H&M can fulfill the promises they made in 2013.

"They promised to get our lives better, but we don't get enough salary and working situation," said Nath Sou, 39, who works at a garment factory near Phnom Penh, Cambodia, which supplies clothes to H&M.

Ms. Nath said she gets $140 a month and must borrow money to pay her rent and support her family. Ms. Sou said that she could be fired for joining a labor union or protesting.

"We do not see who or what company could make our lives better," she said.

Neou Vannarin contributed reporting from Phnom Penh, Cambodia.