An injured Long Panha (C), an employee of the Cambodian Confederation of Unions, is taken into custody by police during a demonstration by garment workers yesterday in Phnom Penh. Photograph: supplied

A union employee representing striking workers from a factory that supplies Levi’s and Gap was left a bloodied mess near Wat Botum yesterday after police allegedly attacked him.

According to rights groups, police set upon Long Panha, of the Cambodian Alliance of Trade Unions (CATU), who was among a group of 20 unionists who had marched from a protest in Freedom Park to deliver a petition to Prime Minister Hun Sen.

A video posted on YouTube yesterday shows police armed with sticks and shields forcing Panha to the ground before carrying him by his hands and feet to a police truck while blood dripped from his face.

Licadho director Naly Pilorge was one of many NGO officials to condemn the incident.

“All eyes are on Cambodia right now as it hosts this important international summit [ASEAN],” she said. “Yet a unionist is beaten bloody on the street during a peaceful gathering – a unionist who is working to improve conditions for workers who supply some of the world’s largest clothing manufacturers.”

Workers from Tai Yang Enterprises first went on strike in May to defend their seniority pay, then again on June 25, to demand accommodation, performance and maternal bonuses.

Over 100 met in Freedom Park yesterday to continue the strike.

Cambodian Confederation of Unions president Rong Chhun said he too had been hurt during the clash while marching to the prime minister’s Cabinet.

Dave Welsh, country director of the American Center for International Labor Solidarity, urged a quick resolution for workers.

“You can’t avoid your collective bargaining rights simply by changing your name and re-incorporating,” he said.

Tai Yang official Ou Menghour declined to comment yesterday, but has previously said the factory did not change its name.

Phnom Penh police chief Touch Naroth declined to comment.

To contact the reporter on this story: Sen David at [email protected]

With assistance from Dagmarah Mackos and Shane Worrell