Four workers arrested on Friday for allegedly throwing rocks during unruly garment worker strikes in the Svay Rieng province border town of Bavet were charged with several crimes at the provincial court yesterday, sparking fears of a further crackdown.

“In this case, they were arrested red-handed throwing rocks into a factory,” said provincial prosecutor Kong Chankhemrith.

“We charged them with violence, damage and incitement to commit crimes.”

By Thursday, some 30,000 garment workers across several major special economic zones (SEZs) in Bavet were on strike over what they maintained was an insufficient increase to the national garment sector minimum wage.

Next year’s wage, which was set months ago, will be $140 a month, up from $128 this year.

On Friday, in a bid to quell reported incidents of rock-throwing and other property damage, hundreds of provincial police flooded the SEZs.

Unions, which are largely banned in the SEZs, have denied any involvement in the strikes. No strike leaders have come forth and a solution remains elusive.

According to rights group Licadho, the four charged yesterday are Van Vicheat, 24, Kong Phros, 27, Pal Dinmalyda, 28, and Kheng Sokha, 31, all men.

Van Vichara, the 22-year-old brother of Van Vicheat, tearfully maintained that his brother was innocent yesterday and alleged that he had been beaten by provincial police.

“They tortured my brother to get answers from him – they beat him on his back and legs,” he said. “I was very angry when I saw his injuries; the police should not have done this to him because the camera did not show that he had committed any crimes.”

Koeng Khorn, the Svay Rieng police chief, could not be reached yesterday. Kao Horn, deputy chief of Bavet’s penal police, hung up the phone when asked about Vichara’s allegations.

The charging of the four has fuelled fears on the ground that further government reprisals are in order, said Chea Oddom, the provincial representative of the Cambodian Union for the Movement of Workers.

“They did this in order to break the spirit of the workers protesting to be paid better. We are concerned about our safety after learning of the court’s decision,” he said.

However, Nuth Ngun, the deputy provincial military police chief, said the violence was instigated by “outsiders” and the situation was largely pacified thanks to the presence of 600 provincial and military police.

“The majority of workers came back to work [on Saturday] because our forces have guaranteed and protected workers and prevented more violence,” he said. “We manned our stations until they left their work [on Saturday].

[Today] we will continue to protect them and increase patrols to look for troublemakers.”

Ken Loo, spokesman for the Garment Manufacturers Association in Cambodia, which called for the government to intervene over what it characterised as “riots” in Bavet on Thursday, said the authorities had responded “relatively quickly” to the situation.

“What needs to be done is we need to find out who is behind this,” he said.

William Conklin, country director for the AFL-CIO’s Solidarity Center, said the strikes appeared “very localised”, and did not represent anything like the nationwide garment worker protests that rocked the country in late 2013 and early 2014.

He said the eruption of the strikes, which came more than two months after next year’s minimum wage for the garment sector was announced, could have been due to the lack of a union presence in the SEZs.

“The story we heard was that the workers did not know what the minimum wage was [until last week] – they thought they were going to get a $20 [raise] again,” he said. “In those zones without unions, you wouldn’t have someone on the ground communicating that.”