Police briefly arrested three union representatives amid a demonstration of more than 1,000 shoe-factory workers in Kampong Chhnang, saying workers should be only allowed to submit letters, not protest.

At least 5,600 workers at Can Sports Shoe, a supplier for Adidas, gave thumbprints supporting a strike about 35 demands that have accumulated over several years, according to workers and labor rights groups.

Only a few hundred went into work on Tuesday as more than 1,000 workers gathered outside the factory in Samakki Meanchey district’s Sethei commune and blocked a road, they said.

Deputy provincial police chief Ear Bunthoeun said three union leaders had been arrested, but released after they agreed to stop organizing chaos.

“If workers want to demand benefits, just let them do it and submit letters. But we can’t allow inciters to provoke demonstrations and work stoppages,” Bunthoeun said.

Public order could be disrupted by demonstrations, he said. The workers had blocked National Road 5, which could suffer traffic jams even with short disruptions, he added.

Noem Sokhoeun, one of the arrested union leaders, said he had been accused of incitement to commit a felony.

“I think it’s a violation of my rights,” Sokhoeun said, adding that he had not organized the protest himself.

The contract he signed on Tuesday says he promises not to gather workers for protests or demonstrations that cause chaos in the factory, and not to commit any acts in the factory against the law.

According to labor rights group Central, the two other union leaders are Sean Sokleab and Pen Sophorn.

Patrick Lee, legal consultant at Central, said: “My view is that these union leaders have been arrested for the sole purpose of attempting to restrict workers’ fundamental right to peacefully strike. The authorities should be acting as mediators and not use their power to restrict workers’ rights and freedoms.”

A list of 35 demands from the workers details accumulated grievances related to payment schedules and methods, medical facilities at the factory, and the availability of food vendors and allowances.

Factory worker Kan Savy said more than 1,000 workers had protested on Tuesday, while another worker, Nou Sitouch, estimated that most of around 8,000 striking workers at the factory gathered outside from around 6 a.m. to 9 a.m.

Yang Sophorn, the president of Cambodian Alliance of Trade Unions, said Can Sports Shoe had more than 10,000 workers in total, and some grievances stretched back two decades.

Two of the union leaders had been arrested Monday evening even before the protest was held, Sophorn added.

“It’s inappropriate as the authorities have the duty to give justice to people and workers,” she said, adding that the factory union had informed the employer about the peaceful demonstration.

“This is a means of threatening workers who are just peacefully exercising their legal rights as stated in the law.”

A woman who picked up on a number listed with the Garment Manufacturers Association in Cambodia for the factory denied she was part of factory management.