PHNOM PENH - The pandemic risks triggering a race to the bottom that could push tens of millions of Asian garment workers into greater hazard on the factory floor, with women hardest hit, the International Labor Organization said on Wednesday.

About 40 percent of workers furloughed or laid off by the COVID-19 crisis were not back at work by the third quarter and those who do return could lose hard-won labor rights, the agency said.

"Workers are extremely vulnerable and factories are vulnerable to agree to conditions with brands that don't allow them to ensure proper working conditions," said Tara Rangarajan of the ILO's Better Work program.

"It's important … that this doesn't become a race to the bottom where those at the lowest end of power and privilege are the ones that suffer the greatest," she said at the launch of an ILO report on the pandemic's effect on garment workers.

Garment workers have been heavily hit by the pandemic, with shops closed and factories shuttered.

Fashion brands cancelled billions of dollars worth of orders from suppliers around the world, costing workers up to $5.8 billion in lost wages, according to advocacy group Clean Clothes Campaign.

In the Asia-Pacific - home to about 65 million garment workers - orders from big Western buyers fell by up to 70 percent over the first half of 2020, costing the average worker between two and four weeks' salary, said the United Nations agency.

While the industry has stabilized in some centers, in Bangladesh, where at least 70,000 workers have been laid off, fears are growing that many will become destitute.

"Given that the situation is worsening, I think we can all imagine what that would mean," said Christian Viegelahn, a senior economist for the ILO in the Asia-Pacific.

The crisis has given rise to union busting in Cambodia, Thailand and Myanmar and seen countries introduce harsh laws that activists fear could be used to restrict worker rights.

Women make up the majority of garment factory staff and have born the brunt of the crisis, Viegelahn said.

"There is significant risk that we see existing inequalities between women and men exacerbated and some of the progress we have seen over recent years will be reversed."

The researchers studied Bangladesh, China, Cambodia, Vietnam, Sri Lanka, India, Indonesia, Myanmar, Pakistan and the Philippines, with uncertainty due to last for months - at least.

Mohammad Akash has reverted to transporting stones for about $2 a day since he was laid off from a Dhaka garment factory.

"It pays half what I used to earn and its twice as painful," he told the Thomson Reuters Foundation.

The 33-year-old lost his job in March and said he is still waiting on severance pay and other benefits promised by the bosses he had served for eight years.

"I haven't been able to pay rent for my house in four months," he said.