DHAKA (Reuters) - Bangladesh police used water cannons and teargas on Thursday to disperse hundreds of garment workers staging a hunger-strike to demand back-pay and a holiday bonus.

The authorities also detained union leaders as well as some workers who smashed vehicles and pelted police with stones to show solidarity with their colleagues on strike.

About 1,600 workers from five factories of the Tuba Group have been on hunger strike since July 28, demanding the payment of salary for three months, overtime and a holiday bonus. The Tuba Group owned the plant at which 112 workers were killed in 2012 in Bangladesh’s worst factory fire.

Officials at the company were not available for comment.

Mohammad Atiqul Islam, president of the Bangladesh Garment Manufacturers and Exporters Association (BGMEA), told reporters on Thursday that almost half the workers had agreed to its offer to pay two-month of back wages this week.

Under the offer, the Tuba Group would pay the rest of the salaries and a bonus at a later date. Union leader Moshrefa Mishu, however, said the workers still rejected the deal.

Mishu was among the union leaders arrested by police.

Low labor costs and, critics say, shortcuts on safety, make Bangladesh the cheapest place to make large quantities of clothing and the second-largest exporter of readymade garments.

The $24 billion export industry, which supplies many Western brands such as Wal-Mart, Tesco and H&M, has been under scrutiny since last year when a building housing factories collapsed killing more than 1,130 people.

The factory collapse came five months after the 2012 fire at the Tuba Group’s Tazreen factory. The owner of the group, Delwar Hossain, was released this week on bail after being detained since February when he turned himself in to face homicide charges.

Last year, the government raised the minimum wage for garment workers by 77 percent to 5,300 taka ($68) a month and amended the labor law to boost workers’ rights.

The industry accounts for 80 percent of Bangladesh’s exports and employs nearly 4 million workers, most of them women.