Slovakia's ruling coalition is in turmoil following the decision to acquire the Russian-made Sputnik V COVID-19 vaccine.
Slovakia became the second European Union member state after Hungary to purchase doses of the Sputnik V vaccine following a secret deal orchestrated by Prime Minister Igor Matovic.
The Russian-made vaccine has not been approved by the European Medicines Agency (EMA), which started its rolling review of Sputnik V on Thursday.
Two of the four parties making up the centre-right ruling coalition have publicly disagreed with the decision.
The Freedom and Solidarity (SAS) party told Euronews that it "would welcome the purchase if Sputnik V was registered with the EMA or at least evaluated by the State Institute for Drugs Control (ŠÚKL)."
"As our Foreign Affairs Minister Ivan Korčok said," the spokesman for SAS added, "it was clear that Sputnik V was not only a vaccine, but a tool of hybrid war."
The party's leader, Richard Sulik, has often clashed with Matovic over how to tackle the pandemic. The eastern European country has the world's highest COVID-19 death rate relative to the population with more than 18.6 deaths per million inhabitants, according to Our World In Data.
"We need to talk about the responsibility for the current state of the pandemic in Slovakia," the SAS spokesman said. "It cannot go on like this any longer. We need to change the culture of ruling."
The party has called for a wide reshuffle of the cabinet.
The For the People party has also criticised the government over the Sputnik V decision and has not ruled out leaving the coalition.
The head of the party, Deputy Prime Minister Veronika Remisova, wrote earlier this week on Facebook that the For the People is "against vaccinating in Slovakia with unregistered vaccines, from any country."
"It's absurd how Igor Matovic welcomed the (Sputnik V) vaccine in Slovakia, he didn't do it with any other vaccine," she went on, arguing that rolling out the vaccine despite it not being approved by regulators "can harm and disregard the system of vaccination in the Slovak Republic."
"The situation in the coalition is serious," she stressed on Wednesday following talks between the different partners.
Matovic acknowledged that he acquired the Russian vaccine against the will of his partners but urged them not to use the conflict to destroy their coalition.
"As the prime minister, I think it's my duty to do the maximum to save the lives and health of people in Slovakia," he said in a video message.
Parliament speaker Boris Kollar, the leader of the fourth coalition party, We Are Family, called on his partners to put aside their disputes and negotiate a way to move forward.