Ukraine's parliament has passed a new set of legislation in an apparent bid to suppress protests against President Viktor Yanukovych.
The laws, backed by 235 out of 450 politicians on Thursday, made blockading public buildings punishable by up to five years in prison and protesters wearing masks or helmets will face a fine or an administrative arrest.
The legislation also simplified a procedure to prosecute lawmakers.
Defamation via the Internet was also banned and would be punishable by a fine or corrective labour of up to one year.
People and organisations which provided facilities or equipment for unauthorised meetings would be liable to a fine of up to $1,275 or detention of up to 10 days.
The sweeping legislation caused an outcry among opposition leaders who fear that the government would use the new legislation to prosecute them and break up the protest movement.
"The regime of Viktor Yanukovych and the Regions Party have completely destroyed state power in Ukraine," said Arseniy Yatsenyuk, leader of Batkivshchyna (Fatherland) party.
"This is nothing else but an overthrow of the constitutional system and a power grab in Ukraine."
Last month, hundreds of thousands took to the streets in the capital, Kiev, and western Ukraine after Yanukovych decided to scrap key political and trade agreements with the EU.
The protests have since dwindled, but the opposition maintains a protest camp on Kiev's central Independence Square known locally as the Maidan.
Opposition politicians regularly use a stage in the square to broadcast messages of support to the protesters and the law, assuming it is signed into force by Yanukovich, would clearly make such action illegal.
The decision in parliament, taken suddenly by a show of hands which caught the opposition off-guard, followed a court ban on protests in Kiev, boosting opposition fears of an imminent police crackdown.