Fifty-five years after he masterminded the crushing defeat of the French empire in Indochina at Dien Bien Phu, Vietnam's famous General Vo Nguyen Giap is still fighting. Only now the 97-year-old's weapons are words - and the battleground is the environment. In January, General Giap, a national hero who was a close confidante of the late president Ho Chi Minh, released an open letter calling on the government to halt plans to mine huge bauxite deposits in the Central Highlands, citing environmental damage, harm to ethnic minorities and even a threat to national security. The Vietnamese government is committed to mining an estimated 8 billion tonnes of bauxite, two-thirds of which is located in the Central Highlands province of Dak Nong. The Chinese aluminium corporation Chinalco has been granted a contract for one of the mines, despite Vietnam's long history of conflict with, and distrust of, its northern neighbour. The critical stance of General Giap, now physically frail but still mentally sharp, has inspired others. In a rare expression of public protest in this one-party communist state, 135 intellectuals last month signed a petition against the project, which was delivered to the president of the National Assembly in Hanoi. They called on the government to stop any further development of bauxite projects in the Central Highlands until a serious investigation of the environmental impact had been completed. Prime Minister Nguyen Tan Dung has termed bauxite exploitation 'a major policy of the party and the state', but has backtracked in the face of the unprecedented pressure from a growing environmental lobby. Last month, the government convened a seminar attended by 50 scientists to address environmental issues, and Mr Dung agreed to scale back the development until an environmental study had been made. According to Vo Quy, one of Vietnam's leading specialists in biodiversity and environmental protection, 'the damage to the environment and agriculture would far outweigh any economic benefits' to be gleaned from the mines. Professor Quy described the Central Highlands as ' a fertile plateau, an area of stunning beauty with rich eco-tourism potential and a highly productive agricultural zone'. He added: 'I support economic development, but not bauxite mines.' General Giap, an intellectual, assisted Vietnam's ecologists back in the 1980s when he held the position of deputy prime minister in charge of science and technology. His January letter reminded Mr Dung that Vietnam had studied the issue of bauxite mining and received advice from experts from the former Soviet Union in the 1980s. 'They warned that it would cause devastating, long-term ecological damage,' he wrote. Amid the flurry of criticism, Mr Dung has frozen work on one bauxite mine but has permitted Chinalco to proceed with the Tan Rai mine project in Dak Nong province. However, Environment Minister Pham Khoi Nguyen has now also joined criticism of the mine projects, after an inspection of the sites last week. In addition to the environmental concerns, some critics have complained about the presence of hundreds of Chinese workers in the strategic Central Highlands. Moves to accommodate China over the Chinalco mine at a time of unresolved territorial disputes over the Spratly Islands has alarmed some Vietnamese. Other opponents question the mines' economic feasibility, given that bauxite processing requires a lot of water and access to cheap electricity - and Vietnam is facing shortages of both. Nguyen Huu Ninh, who was part of a UN team awarded the 2007 Nobel Peace Prize for their work on climate change, was adamant that 'there is no sense in a project that does not bring benefits to local people'. Dr Ninh paid tribute to General Giap's 'green credentials'. 'Giap has a good understanding about ecology, and was our first leader after the war to focus on environmental problems,' he said.