Article published on the 2008-08-24 Latest update 2008-08-24 15:11 TU
Organisers claim that 200,000 people have surrounded the site where the factory is being built. Police, who have mobilised 4,000 officers and sealed the gates to the site, put the figure at about 40,000.
Demonstrators blocked main roads near the plant at Singur, 35 kilometres north-west of the state capital, Kolkata, and heard state opposition leader Mamata Banerjee demand that some of the land be returned to the farmers.
"Our agitation will remain peaceful unless we are provoked," she told the protest rally.
On Friday Tata boss Ratan Tata threatened to move the plant out of the state if the demonstrations continue. The protesters say they will carry on until 400 acres (160 hectares) are handed back to farmers who have refused compensation.
Rabindranath Bhattacharya, a member of Banerjee's Trinamool Congress Party who represents Singur in the West Bengal State Assembly, says that will leave another 600 acres which is enough for car production, which is due to start in October.
"I do not want that Tata should go from West Bengal," Bhattacharya told RFI. "I want that Tata should stay in West Bengal in Singur only in the 600 acres which already willingly the cultivators have decided to give their land."
Tata has invested more than three hundred million euros in Singur project.
West Bengal Chief Minister Buddhadeb Bhattacharjee said the protests would fail.
"The project will be a reality," said Bhattacharjee late Saturday. "Nobody can obstruct it. It is totally impractical to give back the land as demanded. Returning the 400 acres means scrapping the entire project."
There have been protests at the Tata factory site for more than two years, while last year in another West Bangal village police shot dead 14 farmers opposing the construction of a petrochemical hub.