Putin is wanted under an arrest warrant from the International Criminal Court for illegally deporting children from Ukraine.
His visit to Budapest for a summit with a counterpart will be an awkward spectacle for the EU and NATO, given Hungary's membership in both organizations.
President said on Thursday he may meet his Russian counterpart in Budapest within two weeks, adopting a more conciliatory tone towards Russia.
The choice of Hungary for the summit has raised eyebrows among diplomats and analysts, as it is part of the groupings that have helped Ukraine and isolated Russia.
Author's summary: Putin's Budapest visit sparks controversy.