Thousands of people have already contributed 750,000 euros ($798,000) since Monday, when the "Peace for Ukraine" group launched the initiative, organisers said.

Since coming to power last year, populist Slovak Prime Minister Robert Fico has stopped military aid to Ukraine and advocated for peace talks with Russia.

"We, the residents of Slovakia, want to and can help," said Zuzana Izsakova, a representative of the fundraising initiative.

"We want to show that it is not only the government and Robert Fico who decide on this matter," she told AFP.

The organisation hoped to raise one million euros and plans to funnel all of the money to an international initiative spearheaded by the Czech Republic to buy ammunition for Ukraine.

The Czech prime minister said Tuesday that 20 countries had pledged enough to buy 500,000 artillery shells for Ukraine outside Europe.

The Slovak government has not joined the initiative.

One of the donors, Tomas Benetin, cited that as his main motive to contribute.

"I wanted the world to know that Slovakia does not only consist of pro-Kremlin politicians," the 36-year-old from Kosice told AFP.

In recent months, Fico has made a number of inflammatory comments over Russia's invasion, questioning Ukraine's sovereignty and calling for Kyiv to cede territory to Moscow to end the war -- something Ukraine has repeatedly ruled out.

Earlier this month, Fico's longtime ally Peter Pellegrini won a presidential election in the EU and NATO member of 5.4 million people, after divisions over the Ukraine war dominated the vote.

- 'In the right hands' -

Marian Kulich, a representative of "Peace for Ukraine", said the crowdfunding campaign was born out of opposition to the government's stance on Ukraine.

"We are convinced that many people in Slovakia do not identify with the rejection of the Czech government's initiative," Kulich told AFP.

Izsakova said the group wanted to match the one million euro ($1.05 million) donated by the Slovenian government last month.

One supporter of the Slovak crowdfunding campaign is Holocaust survivor Otto Simko, who said his own wartime experiences could be applied to events in Ukraine.

The 99-year-old former journalist took part in the 1942 Slovak National Uprising, an attempt to resist German troops during World War II.

"We fought the aggressor, the German occupation... It was impossible to negotiate with them, they had to be defeated," Simko said in a campaign video for the ammunition initiative.

"If I can only give 20 euros to buy one single bullet, I will know that this bullet is in the right hands," he added.

Another supporter of the fundraising initiative, filmmaker Pavol Pekarcik, pleaded for donations having spent months in the war-torn Ukraine shooting documentaries.

"The feeling of helplessness is probably the worst thing a person can experience in their life," he said in a video message promoting the campaign.

"This is how we can help the Ukrainian defenders so that when someone shoots at them, they don't have empty hands," Pekarcik added.