Opposition politicians spoke with the crowds, who were protesting new rules exempting people who have been vaccinated against coronavirus from some restrictions.
Protesters against vaccine rules blocked entry to Slovakia’s parliament on Friday.
Opposition politicians joined the crowds in the capital Bratislava, who were protesting against new rules -- set to be passed by parliament -- which would exempt people vaccinated against COVID-19 from some of the country’s restrictions.
One policewoman was injured as officers tried to move hundreds of protesters.
They used tear gas to disperse people who were seemingly attempting to break into the parliament building.
Opposition politicians Marian Kotleba from the ĽSNS party and SMER-SD's Ľuboš Blaha came to speak to the crowds.
Kotleba told Markiza TV that he supported and agreed with the protesters.
"They're for our rights, for my rights. They all fight for everybody who rejects obligatory vaccination," he said.
"I did not call the demonstration. The situation is so critical that people should be directly in parliament,” he added.
Prime Minister Eduard Heger said he sympathised with those tired of the measures, but the rules were in place "to protect the lives of all Slovak citizens - even those protesters".
Juraj Krúpa, an OL'ANO party MP said: "I don't know, what should I say. Demonstrations like this are everywhere. Everywhere is a group of people who are fooled by disinformation and became anti-vax."
"We have here lots of deranged people, who risk not just their lives, but also the lives of others. Incidents are not just in front of parliament but throughout the city,” he added.
“For example, they try to get on public transport without masks. Something needs to be done to those people."