Pellegrini, 48, replaces as head of state Zuzana Caputova, who did not stand for re-election
Pellegrini, 48, replaces as head of state Zuzana Caputova, who did not stand for re-election AFP

Peter Pellegrini, an ally of Ukraine-sceptic Prime Minister Robert Fico, was sworn in as Slovakia's new president on Saturday, pledging to unite the politically polarised central European country.

Analysts have predicted Slovakia's international isolation will increase with Pellegrini as president and expect the government to crank up its pro-Russian rhetoric now that its ally is head of state.

Fico, a populist who is recovering from being shot at close range on May 15, has governed a country that has been deeply split for years between pro-European and nationalist-leaning camps.

"Politics should not divide," Pellegrini said in his inauguration speech.

"It shouldn't become a driver of negative and destructive emotions."

The new president, himself a former prime minister, was elected in April with 53 percent of the vote.

He defeated pro-West diplomat Ivan Korcok in a ballot dominated by divisions over the war in neighbouring Ukraine.

Although the office is largely ceremonial, Slovakia's president is the commander-in-chief of the armed forces, ratifies international treaties and appoints top judges.

Analysts have said this could help Fico wield influence over the judiciary and thus strengthen his position.

Pellegrini, 48, replaces as head of state Zuzana Caputova, who did not stand for re-election.

In his speech on Saturday, he said Slovakia was divided by "a high mental wall".

"Today, that wall is splattered with blood," he said in reference to the attempt on Fico's life.

"And if we don't want more blood added, we need to knock this wall down together."

He said the attack, which government ministers have said was carried out by a "lone wolf" for political motives, "undermined not only the prime minister's health but also our certainty that such an event will not occur again in Slovakia".

Pellegrini said he would "reunite" Slovakia.

The new president is a longtime ally of Fico, who has questioned Ukraine's sovereignty and discontinued military aid to Kyiv.

Outgoing president Caputova, a staunch Ukraine supporter, had been a counterweight to the government coalition including Fico's Smer party, Pellegrini's Hlas and the small far-right SNS.

Fico won a fourth term in office in October, with Smer pledging "not a single bullet for Ukraine".

Pellegrini -- who will stand in for Fico at Monday's informal summit of European Union leaders in Brussels -- has played down the impact of his election on foreign policy.

On Saturday he insisted: "Slovakia is, and will remain, a solid member of the European Union and the North Atlantic Alliance (NATO)."

"But it will not be afraid to exert its sovereignty," he added.

Analysts say Pellegrini will have trouble remaining neutral, despite his assurances.

"No one believes that. Being a non-partisan president will be hard work for him," political analyst Tomas Koziak told AFP.

"People who voted for him think this (Pellegrini's stance) is a tool to assist the government coalition," he said.