“We are witnessing a breach of human rights because the Vietnamese [workers] are working in terrible conditions,” Serbian activist Miso Zivanov of the Zrenjaninska Akcija (Zrenjanin Action) non-governmental organisation said.

“Their passports and identification documents have been taken by their Chinese employers,” he said. “They have been here since May, and they received only one salary. They are trying to get back to Vietnam but first need to get back their documents.”

Workers sleep on bunk beds without mattresses in barracks with no heating or warm water. They said that they have received no medical care even when they developed coronavirus -like symptoms, being told by their managers simply to remain in their rooms.

Nguyen Van Tri, one of the workers, said nothing has been fulfilled from the job contract he signed in Vietnam before embarking on the long journey to Serbia.

“Since we arrived here, nothing is good,” he said. “Everything is different from documents we signed in Vietnam. Life is bad, food, medicine, water … everything is bad.”

Wearing sandals and shivering in the cold, he said about 100 of his fellow workers who live in the same barracks have gone on strike to protest their plight and that some of them have been fired because of that.

Linglong did not respond to a call seeking comment but denied to Serbian media that the company is responsible for the workers, blaming their situation on subcontractors and job agencies in Vietnam. It said the company did not employ the Vietnamese workers in the first place. It promised to return the documents it said were taken to stamp work and residency permits.

The company denied that the Vietnamese workers are living in poor conditions and said their monthly salaries were paid in accordance with the number of working hours.

Populist-run Serbia is a key spot for China’s expansion and investment policies in Europe, and Chinese companies have kept a tight lid on their projects amid reports they run afoul of the Balkan nation’s anti-pollution laws and labour regulations.

Chinese banks have granted billions of dollars in loans to Serbia to finance Chinese companies that build highways, railways and factories and employ their own construction workers. This is not the first time rights groups have pointed out possible breaches of workers’ rights, including those of Chinese miners at a copper mine in eastern Serbia.

Serbia praises ‘steel friendship’ with China amid growing economic ties

After days of silence, Serbian officials spoke against “inhumane” conditions at the construction site but were quick to downplay Chinese responsibility for the workers’ plight.

Serbian Prime Minister Ana Brnabic said she “would not rule out that the attack against the Linglong factory” is organised “by those against Chinese investments” in Serbia – referring to frequent criticism from the West that Chinese projects there are not transparent, are ecologically questionable and are designed by Beijing to spread its political influence in Europe.

“At the beginning, it was the environment. Now they forgot that and they focused on workers there. After tomorrow there will be something else,” she said.

Serbian President Aleksandar Vucic said on Friday that a labour inspector has been sent to the Linglong construction site but was blunt on the expected outcome of the eventual findings.

“What do they want? Do they want us to destroy a 900 million-dollar investment?” Vucic asked.