KIEV (AFP) - Hundreds of angry demonstrators in Kiev issued an ultimatum to authorities Sunday, demanding amnesty for fellow activists just hours after vacating the highly symbolic headquarters of a protest movement rocking Ukraine.
"We are issuing an ultimatum to authorities - if they do not immediately announce the complete and unconditional rehabilitation (of protesters) in some 2,000 cases, we will retake city hall," Andriy Illenko, a lawmaker from the nationalist opposition Svoboda (Freedom) party, told protesters.
"This ultimatum expires in several hours," he warned, as around 150 protesters gathered in front of the building, some wearing helmets and army jackets, hitting metal batons on the ground.
The opposition had occupied Kiev's city hall since December as part of anti-government unrest that has raged in Ukraine for close to three months after President Viktor Yanukovych ditched a key EU trade pact in favour of closer ties with Russia.
But in a conciliatory gesture early Sunday, up to 700 protesters evacuated the building in response to a last-minute concession by authorities who on Friday released all protesters detained in unrest.
The interior ministry said occupied government buildings in four other cities in Ukraine had also been vacated.
But Kiev's iconic Independence Square remained under opposition control - the sprawling anti-government enclave protected on all sides against riot police by manned barricades - as did several other buildings in the capital.
The evacuations were one of the conditions set in an amnesty law approved by Yanukovych early this month, promising to heed opposition demands to release detainees and drop charges against them.
Some protesters - including at least one disabled man and a retiree - have been slapped with charges carrying a sentence of up to 15 years in jail.
On Friday, just as negotiations between the warring parties had wound down, authorities unexpectedly announced they had freed all 234 people detained in the protest movement and promised to drop charges too if some occupied parts of Kiev were vacated.
In Brussels on Sunday, EU foreign policy chief Catherine Ashton hailed the release of the detainees but called on Kiev to keep its word and drop all pending court cases against protesters.
"I expect such action to be taken without delay so as to facilitate the political dialogue in (Ukraine's) parliament this week," she said.
But many taking part in a mass rally on Sunday near city hall were unhappy with the decision to evacuate what had become the "headquarters of the revolution."
"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 come from northern Ukraine.
"Yanukovych will take other (protesters) hostage. We can't beat a retreat. Otherwise we will all go to prison."
In a bid to reassure them, opposition leader Arseniy Yatsenyuk said that unless all charges against protesters were dropped, "we will launch a peaceful offensive." He did not elaborate.
Vitali Klitschko, another key opposition figure, acknowledged that many thought the evacuation was a tough price to pay for fellow activists to be released.
"But when you're behind bars, you don't have the same outlook," he said.
Both men will be travelling to Berlin to meet with German Chancellor Angela Merkel on Monday and press her for European financial assistance.
The opposition has also agreed to vacate part of Grushevsky Street, where deadly riots took place in late January, to allow traffic to move freely.
On Sunday, an opening had been carved out in one of the street's barricades, but this was still fiercely guarded by a row of protesters in combat gear.
Nearby, opportunistic vendors sold calendars and magnets depicting scenes of the months-long unrest.
But protesters still have a host of unmet demands, including a major reform of the constitution to reduce presidential powers in favour of the government and parliament.
And ultimately, they want Yanukovych himself to leave.
Andreas Umland, a political scientist at Kyiv-Mohyla Academy in the Ukrainian capital, said the government and opposition were thought to be negotiating a form of power-sharing to be implemented before early presidential elections are held.
"For now the main question is whether Yanukovych will agree to power-sharing, what kind of power-sharing and how much power will be left to the office of the president," he said.