Up to 190 of the 312 Chinese labourers at Nhan Co Aluminum Plant in Dak Nong province are working without the right paperwork, online newspaper Viet Nam Net said.

It is the second such case this week, after Tuoi Tre newspaper reported Tuesday that the construction site of a urea plant in Ca Mau province employs over 1,000 Chinese labourers without permits.

The problem was the fault of Vietnamese labour contract agencies, President Truong Tan Sang said at a meeting with voters in Ho Chi Minh on Thursday, according to a separate report in Tuoi Tre.

'It is normal for workers to go from country to another to work,' he was quoted as saying. 'The issue is that those workers must comply with the laws of the country where they are working.'

The two Chinese-run mines have sparked fierce criticism in the country.

Several high profile critics, including war hero General Vo Nguyen Giap, have also pointed to the environmental damage as well as the displacement of ethnic minorities in the area.

Reports that many were working illegally have sparked a crackdown in visa policies in recent years.

In April 2010, 40 Chinese workers were expelled from a Singaporean sand excavation project in Ba Ria Vung Tau province. The workers had entered the country on tourist visas and had no work permits.

Deutsche Presse Agentur - August 12, 2011