KIEV (AFP) - Protesters arrested during months of anti-government unrest in Ukraine were granted amnesty on Monday after the opposition agreed to end their occupation of Kiev city hall and other public buildings.

The law dropping charges against the protesters came into effect a day after activists vacated the buildings they had occupied in anger over President Viktor Yanukovych's decision to reject an EU trade deal in favour of closer ties with Russia.

However nearly three months after the protests began, the opposition remains firmly entrenched in their sprawling tent city on Kiev's iconic Independence Square, vowing to keep up pressure on the authorities.

Yanukovych conditionally approved the law at the beginning of the month as he sought to pacify protesters following deadly unrest in Kiev that shocked the country.

The announcement it had been granted came late Sunday after the opposition conceded to the condition they move out of the buildings.

"The (amnesty) law comes into force from February 17, 2014, and stipulates that charges against people having committed offences... will be dropped," Ukraine prosecutors said in a statement.

The opposition concession prompted strong criticism on Sunday at the latest mass rally on Independence Square.

"It's a bad decision... We can't trust the authorities, they're crooks. The opposition is making a big mistake," said Volodymyr Penkivski, a 56-year-old protester, who had travelled from northern Ukraine.

"Yanukovych will take other (protesters) hostage. We can't beat a retreat.

Otherwise we will all go to prison." Vitali Klitschko, the former boxer turned opposition leader, acknowledged that the decision to evacuate city hall, though difficult, was the right thing to do.

"When you're behind bars, you don't have the same outlook," he said.

Some of those arrested had been slapped with charges carrying sentences of up to 15 years in jail.

"I am satisfied," said Ruslan Andriyko, a protester who had managed the day-to-day running of the occupied city hall, which had become the "headquarters of the revolution".

"Despite a difficult decision, we succeeded in overcoming emotions and ensuring that the law came into force," Andriyko said.

Klitschko and Arseniy Yatsenyuk, another opposition leader, will be travelling to Berlin to meet with German Chancellor Angela Merkel on Monday and press her for European financial assistance.