BERLIN (AP) — Hungary's prime minister, one of the strongest European critics of Germany's approach to the migrant crisis, made a politically charged visit Tuesday to former Chancellor Helmut Kohl — Angela Merkel's predecessor and one-time mentor.

Viktor Orban traveled to Kohl's home in southwestern Germany for what was described as a private visit between friends. Still, it has been widely interpreted in Germany as a swipe by Kohl at Merkel over her relatively liberal approach to welcoming refugees.

Kohl, who oversaw German reunification in 1990, has suffered from poor health for several years. He turned 86 a couple of weeks ago, seldom appears in public and also has rarely intervened in political debates recently.

Orban's visit coincided with the publication in Hungarian of an essay on Europe by Kohl with a new foreword from the ex-chancellor. In that, Kohl states that "Europe cannot become the new home for millions of people in need worldwide" and that unilateral decisions, "as well-founded as they may seem on an individual basis," must become a thing of the past.

Merkel and Orban have been on opposite sides of Europe's argument over the migrant crisis. Orban opposes Merkel's attempts to have European Union countries share the refugee burden and went so far as to build a fence to seal Hungary's southern border.

A joint statement released by Kohl's office and the Hungarian Embassy stressed that Europe can only offer sanctuary to a small part of the world's refugees and that "solutions beyond Europe must be found."

It also expressed their commitment to a "politically united Europe," stressing that Orban and Kohl see no conflict with Merkel's efforts to resolve the migrant crisis.

Speaking in Berlin, Merkel sought to dispel any friction. Orban and Kohl made many points, "such as fighting the causes of flight, such as common European action, which are exactly what I consider absolutely essential and important," she said.