His office confirmed the news on Monday after the daily Večer reported that Pahor had a hard time making the decision due to US pressure to snub Putin.

The invitation bears today's date, said the president's office. In it Pahor says that he and Putin have different views on some issues, however, this only "encourages the need for dialogue".

Pahor tells Putin he believes that heads of nations and states should contribute the best they can to mutual respect and understanding and to solidify international peace and security.

The president adds that a century has passed since the avalanche killed more than 100 Russian POWs. Every year, the fatal event is marked by a ceremony at the Russian Chapel, dedicated to the tragedy.

Through the past decades, the ceremony has turned into "an annual symbolic gesture bearing the message of the importance of peace and respect and understanding among nations", Pahor adds.

If Putin accepts the invitation, this will be his third visit to Slovenia. Slovenian media have reported in the past days that the decision to invite the Russian president was a very sensitive internal and foreign policy decision.

Therefore, Putin's trip to Slovenia would not be designated as an official visit and would be exclusively of commemorative nature - without any state honours and official addresses.

Putin might however attend the unveiling of a new monument to Russian and Soviet POWs who died in Slovenian lands at Ljubljana's main cemetery.

Večer also reported that Pahor was under strong pressure from the US not to invite Putin. But this will not be the only high-ranking visit of its kind. Shortly, a delegation of senior officials from Austria is to travel to Russia, while Putin will visit Finland in June.

What is more, Putin visited Rome and the Vatican last year, meeting Pope Francis and Italian Prime Minister Matteo Renzi. He also visited Hungarian Prime Minister Viktor Orban.