Deputies in the Chamber of Representatives, the lower house of parliament, voted 97 to four to back amendments to the Criminal Code that provide tough penalties for anyone convicted of inciting demonstrations or spreading information deemed to discredit Belarus.
Under the new law, public appeals for the overthrow of the government or "the forcible change of the constitutional system" would be punishable with prison terms of up to three years.
Spreading of "false" information about the situation in Belarus would be punishable by up to two years in prison. Critics of the law say it is aimed to prevent upheavals like Ukraine's Orange revolution one year ago.
Lukashenka submitted the bill to parliament on 23 November for "urgent" consideration. Two days later, deputies passed it in a first reading.