Despite protests from environmentalists and local citizens, the government is allowing the mining to expand beyond previously set limits to get access to up to 120 million metric tons of coal in the northwest of the country.
The limits were set in 1991 to prevent environmental damage as brown coal is a major source of greenhouse gases.
Trade and Industry Minister Jan Mladek says the coal is needed to secure the country's energy supply.
Tuesday's decision still prohibits mining that might affect populated areas. Mladek, however, says the government will reassess the country's need of lignite every year until 2020.