EU foreign affairs head Catherine Ashton said Friday she was "deeply concerned" after Ukraine passed laws to curb the right to protest, a move the opposition called a "power grab."

"I am deeply concerned by the events in Kiev," Ashton said.

"Several pieces of legislation restricting ... citizens' fundamental rights have been hurriedly passed in apparent disrespect of parliamentary procedures and democratic principles," she said in a statement.

"I am particularly concerned by the changes ... which impose worrying restrictions on the rights of assembly and on the freedom of speech and media, and are contrary to Ukraine's international obligations."

On Thursday, pro-government lawmakers passed a series of laws in an apparent bid to suppress protests against President Viktor Yanukovych dating back to November when he ditched an association accord with the EU at the last moment under Russian pressure.

Last month, hundreds of thousands took to the streets and while the protests have since dwindled, the opposition maintains a camp on Kiev's central Independence Square.

The legislation notably made a blockade of public buildings punishable by up to five years in prison and simplified procedures to prosecute lawmakers.

Dissemination of slander on the Internet was also banned and would be punishable by a fine or corrective labour of up to one year.

Ashton said the "changes that seem to seriously curtail the activities of civil society organisations ... and simplify procedures (to oust MPs) are equally worrying."

Such steps "do not contribute to building confidence and finding a political solution," she said.

"I call on the president ... to ensure that these decisions are revised and brought in line with Ukraine's international commitments," Ashton concluded.