Workers want to be paid some or all of their salaries for the days they have been on strike, a common arrangement in France where unions do not have strike funds, according to union representative Pascal Brochard.
The strike at a plant in Carquefour, near Nantes, started on Monday when the company asked for a 50 per cent increase in output, which has declined since the closure was announced.
Unions also complain that the company has failed to explain its restructuring plans to staff.
Seita, which makes the famous Gauloise, is owned by Britain's Imperial Tobacco, which says that sales have dropped over the last six months and that it has been hit by declining sales in Europe, tougher anti-smoking measures and a rise in contraband sales.
Imperial Tobacco announced mid-April the closure of a factory in the British city of Nottingham and the Carquefou factory and a research centre in France with a total loss of 900 jobs.
Imperial Tobacco bought Seita in 2008 and has already cut 1.000 jobs at the Carquefou plant.