KIEV (AFP) -- The European Union and the United States expressed concern after the Ukrainian parliament passed laws to curb the right to protest, a move the opposition called a power grab.

Western rights groups meanwhile denounced the bills passed on Thursday as an attempt by President Viktor Yanukovych to impose a "dictatorship" and called on him to veto the legislation.

The opposition has staged nearly nearly two months of protests in a central Kiev square in response to Yanukovych's ditching a key pact with the European Union and instead striking a strategic partnership with powerful neighbour and past master Russia.

EU foreign affairs head Catherine Ashton said Friday she is "deeply concerned by the events in Kiev," referring to the "worrying restrictions" Verkhovna Rada passed in a slew of bills targeting the pro-EU demonstrators.

Such steps "do not contribute to building confidence and finding a political solution," she said, asking Yanukovych to "ensure that these decisions are revised and brought in line with Ukraine's international commitments."

Washington also voiced concern, with State Department spokeswoman Jen Psaki saying the parliament had "pushed through several controversial measures... without adhering to proper procedures."

"If Ukraine truly aspires to a European future, it must defend and advance universal democratic principles and values that underpin a Europe whole, free, and at peace, and not allow them to be systematically dismantled," Psaki added in a statement.

New legislation introduces punishment of up to five years in prison to people who blockade public buildings, and possible arrest of protesters who wear masks or helmets.

The provisions are clearly aimed at the protesters in Kiev, who are occupying the City Hall building and manning a tent city with massive barricades on Independence Square, also known as the Maidan, and surrounding streets.

Other provisions passed Thursday introduced the term "foreign agent" to be applied to NGOs that receive even the smallest funding from foreign countries, simplified prosecution of lawmakers, and made dissemination of slander on the Internet punishable by a year of corrective labour.

The bills, "if signed by President Viktor Yanukovych, will destroy the manifestations of civil disobedience in Ukraine, begin repressions and turn Ukraine into a dictatorship," said the Ukrainian branch of Transparency International.

Swedish Foreign Minister Carl Bildt said on Twitter Friday that the new bills lead to a situation where "there can be no business as usual with Kiev."

'Bills are a high security prison'

The opposition meanwhile accused Yanukovych of ending democracy in the country and called for a new massive protest on the upcoming Sunday.

"Yanukovych... made a new step toward installing a real neo-dictatorship in Ukraine," the jailed protest leader and former prime minister Yulia Tymoshenko said in a statement.

She called the bills "the final liquidation of Ukraine's parliamentary system."

"The bills are a high security prison for everyone who feels like a free person," said Ukraine's former minister turned opposition leader Yuriy Lutsenko.

He invited all Ukrainians to mount a strong protest against "the ruling group of bandits", writing on his Facebook page while recovering in a hospital from an attack by truncheon-wielding police this month.

Russia passed a similar package of bills after Vladimir Putin was inaugurated for his third historic term in the Kremlin in 2012, hiking fines for unsanctioned protests, making libel a criminal offence, and slapping NGOs with the ominous "foreign agent" label.

"What Russia did in 60 days after Putin's (inauguration), Ukraine did in 20 minutes," the deputy chief of Human Rights Watch group Rachel Denber wrote on Twitter.

Critics voiced concern over the peculiar method of voting in the parliament after the regular electronic casting of votes was changed to a count of raised hands, leaving no record to verify the figure of 235 in favour out of 450 present which was announced by officials.

The opposition sought to disrupt the vote, and the session disintegrated into chaos as lawmakers wrestled and swung fists, drawing blood.