Georgia's government on Sunday issued a warning to protesters that it would arrest anyone who blocked the parliament, ahead of an expected late-evening rally against a Russian-style "foreign agent" bill.
Demonstrations have gripped the tiny Caucasus country for weeks over a bill targeting NGOs, dubbed the "Russian law" as it mirrors repressive legislation used by the Kremlin to silence critics.
Protesters are due to gather outside parliament in Tbilisi late in the evening, with many planning to stay through the night.
"Group blocking of an object of special importance is punishable by up to four years in prison," Interior Minister Vakhtang Gomelauri said.
"We are going to use this article against lawbreakers without any exemption," he warned.
The protest will come a day after tens of thousands gathered in Tbilisi's Europe Square. Protesters said they planned to continue holding rallies, with the government appearing intent on passing the law in the coming days.
"I want to warn everyone from the radical groups of opposition that everyone will be held accountable to the law for violence," Prime Minister Irakli Kobakhidze warned.
Authorities have presented protesters -- largely made up of young people -- as violent mobs.
"At the same time, I would like to ask the law enforcement officers to show maximum patience and act with a higher standard than it is in Europe," Kobakhidze added.
Saturday's rally was peaceful, with rock music blasting out from the stage, but night-time demonstrations have been dispersed in the past.
Powerful billionaire Bidzina Ivanishvili and his ruling Georgian Dream party have said NGOs are a threat to Georgian sovereignty, accusing them of plotting a revolution and working on behalf of foreign governments.
The stand-off over the bill has created one of the most unpredictable and tense political moments in Georgia in recent years.
Protesters say the bill is a move to silence critical voices and is proof Georgian Dream is derailing Tbilisi's long-held ambition of joining the European Union -- supported by the vast majority of the population.
They accuse the government of bringing the ex-Soviet country back into Moscow's fold and of lying in promising a future in the EU.
The protests, led mostly by students and younger generations, are heavy in anti-Kremlin rhetoric, with thousands carrying EU and Georgian flags.
Some also carry Ukrainian flags.
Luka Bereia, a student protest leader, said the bill "threatens us starting negotiations to join the EU."
"We do not want to be out of this game," the 24-year-old said.
He said he planned to stay the night outside parliament and readied for an "extraordinary night", vowing he was not afraid of police force.
Speakers at Saturday's protest called on supporters to gather at 10:00 pm the next day outside parliament and to bring yoga mats with them.
Georgia's pro-EU President Salome Zurabishvili, at loggerheads with the government, warned protesters to be vigilant.
"I want to address you (the protesters), so that you know... There are some plans that will not really work, but there are some plans to organise provocations and involve you," she said, without going into details.
"So stay very careful, which does not mean fear," she added.
On April 30, authorities dispersed a protest using water cannons and tear gas.
Leading NGO activists have over recent days reported being harassed by unknown people, with some having their homes and offices plastered in posters that read "foreign agent".
Georgian Dream has portrayed the bill as being about "transparency" -- saying it is merely an administrative issue.
But the NGO sector, the opposition and protesters say the government's true aims are about control and getting rid of critical voices.
They also say the bill is timed to prepare ground for an autumn election.
