However, Zhou, the employee of the construction company in Kemerovo, said Zhang, a technician for the project, is to blame for the substandard quality of the project.

"The online post and some media reports are not true," Zhou said.

"Quality problems have kept appearing with the construction of the two buildings," she said. "Before construction on the basements of the buildings was completed, we found cracks in the wall and some pillars were displaced," she said. "So we had to suspend the work for eight or nine days so the supervisor could check and verify whether the construction could proceed."

"We suspect Zhang was afraid he might be forced to take responsibility for quality problems, so he incited workers to protest," she said.

Zhang, Heilongjiang's Foreign Affairs Office and the Chinese Embassy in Russia could not be reached for comment on Sunday.

Zhou denied the workers received insufficient pay or were denied freedoms, but families of the workers disagreed.

A woman in Dongbeiyi said her 22-year-old son, surnamed Xu, was working on the project but she had been unable to contact him and was very worried.

"I heard that after they arrived in Russia their passports and cellphones were taken away by the project contractor, and only a few of them who hid their phones managed to call their families," she said.

She said her son was promised a monthly salary of 12,000 yuan, but after he arrived in Russia he was told he would only get 9,000 yuan a month. He received just 5,000 yuan for three months of work because the project contractor said the work was substandard.

"I have heard they have been transferred to a safe place, and I feel a little relieved," she said. "I don't care much about the loss of pay as long as my son is safe. I hope he can return as soon as possible, and I will never allow him to go abroad or go to places far away from home to work."