The report said that arbitrary arrests by the Bangladesh Police are growing with each passing day - nine more union organizers were arrested on February 10, taking the number of known arrests to 34.
HRW asked the Bangladesh authorities to immediately release those still in detention and drop all politically motivated charges.
The organisation also urged global brands and donors attending the February 25, Dhaka Apparel Summit hosted by the country's garment export association to call on the government to stop all persecution of union leaders and protect workers' freedom of association.
"Targeting labor activists and intimidating workers instead of addressing their wage grievances tarnishes Bangladesh's reputation and makes a mockery of government and industry claims that they are committed to protecting worker's rights," said Phil Robertson, deputy Asia director at Human Rights Watch.
"Global garment brands sourcing from Bangladesh and aid donors should press the government to stop persecuting workers and labor rights activists," he added.
Thousands of garment workers outside Bangladesh's capital, Dhaka, participated in wage strikes between December 11 and 19 last year.
They came from an estimated 20 factories that supply global brands based in the Ashulia industrial area.
The Bangladesh authorities used these strikes as a justification to arrest national union federation leaders and labor activists for "leading" and "planning" the strikes.
Workers said that strikes are often the only means for them to raise their grievances because the government and local employers retaliate against union organizers and workers trying to organize as a result, workers are unable to bargain collectively with employers and use formal channels for addressing grievances.
The workers coalesced behind a demand for a monthly minimum wage increase from 5,300 takas (US$67) to 15,000 ($187) or 16,000 ($200).
In 2016, the Fair Labor Association found that the purchasing power of a Bangladesh factory worker's average compensation was below the World Bank poverty line.
Both the Bangladesh Garment Manufacturers Export Association (BGMEA) and the government rejected a wage review.
The export association closed about 60 Ashulia factories for several days, effectively locking out thousands of workers and ending the strikes.
In early January 2017, about 20 global brands sourcing from Bangladesh, including H
M, Inditex, Gap, C
A, Next, and Primark, wrote to Prime Minister Sheikh Hasina supporting a wage review and expressing their concerns that union leaders and worker advocates were targeted.
Rights groups have information about 10 criminal complaints filed in December 2016, implicating about 150 named workers and over 1,600 "unknown" people for crimes, including property destruction at the factories, during the strikes.
Union leaders and organizers have also now been questioned or arrested in relation to older cases.
These groups are aware of 34 people who were arrested, most of them union leaders.
In addition, a journalist from the ETV, a local news channel, was arrested for reporting about the strikes.
A news report from early January suggests the numbers are higher, stating the police had arrested at least 44 people and were identifying another 159 suspects.
The police have not provided a full list of all those arrested and where they are being held.
Based on interviews with rights groups, lawyers, and workers, and police records, HRW found the circumstances of many of the arrests following the Ashulia strikes point to politically motivated abuse of police powers to retaliate against labor organizers rather than credible allegations of crimes.
The Bangladesh authorities should stop pressing these criminal cases and hold any police officers who used forced disappearances, torture, death threats, and other abusive police practices after the Ashulia strikes accountable, Human Rights Watch said.
Based on information from workers, local labor rights groups, and newspaper reports, some Ashulia factories have also retaliated against an estimated 1,500 workers by indiscriminately firing or suspending them.
HRW said that the donors and brands sourcing from Bangladesh have the responsibility to respect and protect workers' rights and called for an end to all harassment of labor leaders, workers, and journalists, including by ending the false criminal cases.
The organisation asked brands sourcing from Bangladesh to make binding agreements with local and global unions to protect freedom of association, modeled on the Bangladesh Accord on Fire and Building Safety, an enforceable agreement between workers and brands with a dispute resolution mechanism.
Voluntary commitments in brands' codes of conduct are ineffective to counter factory retaliation against unions.
HRW also asked brands to ensure their suppliers develop corrective action plans with worker representatives, including the option of reinstating fired workers and negotiating collective bargaining agreements to resolve wage disputes. (ANI)