Slovaks on Saturday cast ballots for a new president with Russia's war in neighbouring Ukraine a key point of contention between the two candidates who went into the election neck and neck in recent polls.

The outcome of the run-off between pro-West diplomat Ivan Korcok and Ukraine-sceptic parliament speaker Peter Pellegrini could impact whether EU and NATO member Slovakia edges further towards Russia in its views on the conflict next door.

Moscow's invasion of Ukraine became a fixture of the electoral campaign in the country of 5.4 million people after populist Prime Minister Robert Fico, Pellegrini's ally who took office in October, questioned Ukraine's sovereignty and called for peace with Russia.

Korcok, a 60-year-old former foreign minister and staunch Ukraine supporter, and the 48-year-old Pellegrini are vying to replace the outgoing liberal President Zuzana Caputova, who has decided not to run again.

They are squaring off in a decisive second round as neither took 50 percent to win outright in last month's initial ballot.

Though the office is largely ceremonial, Slovakia's president ratifies international treaties, appoints top judges, is the commander-in-chief of the armed forces and can veto laws passed by parliament.

After casting his ballot with his wife, Korcok said the election was "partly about the future course of the country".

"I want to make it clear where Slovakia belongs," he said from the western town of Senec, before a bicycle ride and family time.

Voting in nearby Rovinka, Pellegrini said foreign policy was not at issue because whatever the outcome, Slovakia would remain "a strong member of the European Union and NATO".

He said he would rid his nervousness over what promised to be an "extremely tight" race by lunching with his parents and walking his dog.

  'Too close to call' 

Korcok vowed to "serve the people, not the politicians" during his electoral campaign while Pellegrini pledged to "unite a divided Slovakia".

The final pre-election poll by the Focus agency put Pellegrini at 51 percent and Korcok at 49.

"This is the tightest ever presidential race," said Vaclav Hrich, managing director of the AKO polling agency.

Analyst Tomas Koziak told AFP that Korcok was "unlikely" to win over many of the votes that went in the first round to EU critic Stefan Harabin, who finished third with 12 percent.

Yet Hrich said the election was "too close to call" and that turnout would be decisive.

"The more people vote, the more chances Peter Pellegrini will have as this would mean he had succeeded at convincing Harabin's voters."

Because Slovaks cannot vote from abroad, expatriate Jana Kapustova flew back from the United Kingdom to cast her ballot for Korcok.

"He is a guarantee of the continuation of pro-European, democratic politics," the civil enforcement officer, 60, told AFP.

Management consultant Ivan Hriczko, 43, opted for Pellegrini.

The resident of Kosice, eastern Slovakia highlighted his candidate's "decency, rhetoric, behaviour, hard work and service to the country".

Pellegrini was a minister in Fico's previous administrations and premier from 2018 to 2020 after his long-time ally was toppled.

"I am running for president to rescue the government of Robert Fico," Pellegrini said in a televised debate.

Korcok fired back: "You want to protect the government. I want to protect Slovakia."

  War and peace 

 Analyst Koziak said "if Pellegrini wins, Slovakia could go the 'Orban way'," referring to Kremlin-friendly Hungarian maverick Premier Viktor Orban.

The government in office since October includes Fico's Smer party, Pellegrini's Hlas, and the small far-right SNS. It has discontinued military aid to Ukraine.

"Korcok is a warmonger, who will support everything the West tells him without hesitation, including dragging Slovakia into the war," Fico said in a video.

He expressed support for Pellegrini as "a moderate candidate who recognizes the value of peace".

Pellegrini said Slovak politicians were divided into those wanting to continue the war or those advocating peace talks.

"I belong to the latter," he told AFP.

Korcok told AFP that Russia "has trampled on international law. I do not think Ukraine should give up part of its territory to achieve peace".

Pavol Turanec, an electrical designer from Martin, northern Slovakia, hailed Korcok as "a real pro: pro-democratic, pro-Western, pro-European".

"This criminal government is leading us to a pro-Russian autocracy... They need a counterweight," the 50-year-old told AFP.

Jana Mozolova, a retired teacher from Kosice, 66, voted for Pellegrini.

"He has been around for years and never let anyone down."

Provisional results are expected around midnight.