BUDAPEST (Reuters) - Thousands of Hungarians thronged the streets of Budapest on Sunday in the fourth and largest protest in a week against what they see as the increasingly authoritarian rule of right-wing nationalist Viktor Orban.

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Braving sub-zero temperatures, setting off flares and waving Hungarian and European Union flags, about 10,000 demonstrators walked from historic Heroes’ Square toward parliament and then state TV in a march dubbed “Merry Xmas Mr. Prime Minister.”

The march was largely peaceful until police fired tear gas at protesters jostling outside the TV station late at night. Footage showed people crouching and blinded by the gas.

The demonstration was organized by opposition parties, students, and trade unions to demand a free media, withdrawal of a labor law increasing overtime, and an independent judiciary.

“All I want for Xmas is democracy,” read one banner.

Hundreds of police in riot gear shepherded what was one of the biggest demonstrations Orban has faced since he rose to power in 2010 and began wielding his large parliamentary majority to pressure courts, media and non-government groups.

The prime minister projects himself as savior of Hungary’s Christian culture against Muslim migration into Europe, and won a third straight term earlier this year.

On Saturday, Orban’s ruling party Fidesz said “criminals” were behind the “street riots” and accused Hungarian-born U.S. billionaire George Soros of stoking the protests.

Soros is a strong critic of Orban but denies claims against him as lies to create a false external enemy.

Late on Sunday, several opposition lawmakers gained access to the state TV building in Budapest seeking to have a petition read out, but security personnel told them that was impossible.

“The TV is lying!” shouted protesters, of the state channel viewed as mouthpiece for the government.

“Dirty Fidesz!” they added.

“Discontent is growing,” said Andi, 26, a sociology student who did not want to give her full name.

“They have passed two laws this week which ... won’t serve Hungarian people’s interest,” she added, referring to the labor legislation critics dub a “slave law” and new courts for sensitive issues such as elections, protests and corruption.

Frequently clashing with the European Union over his policies, Orban has tweaked the election system to favor Fidesz and put loyalists at the head of institutions, while allies have enriched themselves.

But he has rarely angered large voter groups at home, and the opposition is weak and fragmented.