The website, Bauxite Vietnam, criticizes the Chinese-run bauxite mines in the Central Highlands region on environmental grounds, and Chi's questioning came as Vietnam has been cracking down on dissent in recent months, arresting dozens of people.

Officer Ly Dung of the Ministry of Public Security's A24 security police department confirmed Chi's interrogations were taking place.

Chi's colleague Pham Toan said the questioning was aimed at persuading Chi to shut down his website. Toan said police had tried to uncover evidence of political activity by the website's contributors but maintained that they were not politically organized.

Asked whether he found the sessions tiring, Chi said he would continue as long as necessary.

'I am a steadfast person,' Chi said. 'I never bow my head in the face of dirty work.'

Several Hanoi intellectuals have warned that Chi might be formally arrested in the near future, but Chi said that was unlikely.

Police seized Chi's computer when they searched his Hanoi house, a frequent step taken by Vietnamese authorities in investigating political activists.

The search occurred a week before four democracy activists were sentenced to five to 16 years in prison while in December a democracy campaigner received a five-and-a-half-year sentence and nine dissidents were sentenced in October to terms of two to six years.

The original Bauxite Vietnam website was knocked out by unknown hackers two months ago. A replacement site can be accessed at boxitvn.wordpress.com.

The Chinese state aluminum company Chalco has opened two mines and processing plants for bauxite, or aluminium ore, in central Vietnam in the past two years. Four more are under consideration.

The mines have been controversial since January 2009 when retired Senior General Vo Nguyen Giap, a veteran of the Vietnam War and respected former politician, wrote a letter to the prime minister opposing them on security grounds.

A number of Vietnamese scientists and National Assembly deputies have also criticized the mines for environmental reasons and for employing Chinese rather than Vietnamese workers.

The government promised a full environmental impact assessment of the projects last summer but has not published any so far.

Deutsche Presse Agentur - January 28, 2010