Pope Francis during the first speech of his visit to Hungary called Friday for recovery of the European spirit and rejection of "adolescent belligerence" amid rising nationalism and war in Ukraine.

"It is vital, then, to recover the European spirit: the excitement and vision of its founders... and to generate forms of diplomacy capable of pursuing unity, not aggravating divisions," the pope said. 

His first speech was attended by nationalist Hungarian Prime Minister Viktor Orban, together with other dignitaries, diplomats and members of civil society.

In it, the pope warned against "the soloists of war" taking over as "the maturity attained after the horrors of the war gives way to regression towards a kind of adolescent belligerence".

"More and more, enthusiasm for building a peaceful and stable community of nations seems to be cooling, as zones of influence are marked out, differences accentuated, nationalism is on the rise and ever harsher judgments and language are used in confronting others," he added.

The 86-year-old Argentine pontiff arrived in Hungary Friday for a three-day visit and met Orban, whose views often clash with his own.

While the two men have both called for peace talks to try to end the war in Ukraine, their views on migration differ.

The Hungarian premier regularly espouses anti-migration sentiment to defend a "Christian Europe", while the pontiff has a more welcoming stance towards those fleeing poverty or conflict zones.

During the first speech, the pope emphasised "the need for openness towards others", while warning against "withdrawing into oneself".

"It is urgent then, as Europe, to work for secure and legal corridors and established processes for meeting an epochal challenge that is ineluctable and needs to be acknowledged, in order to prepare a future that, unless it is shared, will not exist," he added.