The professor's website criticizes the bauxite mines run by the Chinese state aluminum company Chalco in central Vietnam on security and environmental grounds.

Contacted by telephone, Chi said he and investigators were "working together in a friendly manner."

Lawyer Cu Huy Ha Vu, who has filed a lawsuit against Vietnam's prime minister over the mines, said he was sure the search was related to the professor's website.

Vu said the original site had been taken down by unknown hackers two months ago. A replacement site can be accessed at boxitvn.wordpress.com.

Chalco has opened two bauxite-mining and -processing plants 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 also have criticized the mines for environmental reasons.

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

Deutsche Presse Agentur - January 14, 2010