Slovak Prime Minister Igor Matovic said Friday he had tested positive for Covid-19, a week after he attended an EU summit in Brussels.

Slovaks began voting Saturday for a new president with the favourite an outsider whose anti-corruption stance has resonated with voters still reeling from the fallout from an investigative journalist's murder.

Slovaks began voting Saturday in round one of a presidential election that a vocal government critic is poised to win after an investigative journalist's murder dealt a blow to the ruling elite.

Two Slovak MPs on Wednesday donned yellow stars symbolizing the Holocaust in protest at the "dangerous" parliamentary debut of a far-right party they condemn as "fascist".

The opposition MPs wore the stars to an inaugural session of parliament following the country's March 5 election in which the Our Slovakia party won 14 seats.

Slovakia's leftist Prime Minister Robert Fico said Sunday he would begin difficult coalition talks after he won elections on a anti-refugee platform but lost his parliamentary majority as smaller parties, including the extreme right, scored first-time seats.

A conservative party leader described the outcome as a "big earthquake" in Slovak politics, as analysts cautioned that Fico would struggle to build a governing coalition with a total of eight parties reaching the five percent threshold to enter parliament.

Slovakia said Wednesday it had mounted a legal challenge to the EU's plan to distribute 160,000 asylum-seekers among member-states under a quota system.

"The Slovak republic has officially filed a lawsuit against the Council of the European Union, to the highest court ... in Luxembourg," leftist Prime Minister Robert Fico said.

European Union leaders, who will gather for an emergency summit on the migration crisis on Wednesday, are expected to give extra funding to Turkey, Jordan, Lebanon and U.N. agencies.

The leaders are hoping that the funding would help stop the flow of refugees to Europe.

Thousands of migrants sought their way through a chaotic maze of rumor and proliferating border controls in the western Balkans on Saturday.

In the latest chapter in the EU's escalating refugee crisis, Croatia, Hungary and Slovenia tussled over how to cope with a wave of refugees desperate to reach northern Europe.

Several dozen migrants entered Croatia from Serbia early Wednesday, the first to enter the EU country after Hungary sealed its borders to thousand of people entering every day, an AFP correspondent saw.

The group of mostly Syrian or Afghan men, women and children crossed the border -- which was marked by nothing more than a stone -- early Wednesday morning and were picked up by police as they walked across a field.

Hungary sealed its border with Serbia on Tuesday to stem the massive influx of refugees as Germany slammed the "disgraceful" refusal of other EU countries to accept more migrants after 22 died in yet another shipwreck.

Budapest's move came after Austria and Slovakian authorities followed Germany's lead in reimposing border controls, a further body blow to Europe's cherished passport-free Schengen zone as the EU's border agency said more than half a million migrants had been counted at the bloc's borders so far this year.