Senior officials from Slovenia and Russia are expected to attend, though Russia's Ambassador to Slovenia Doku Zavgayev pointed out on Tuesday that the event was "non-political and unpoliticized".

The Russian delegation at the ceremony, headlined by Minister of Communications and Mass Media Nikolai Nikiforov, will include representatives of the government and both chambers of parliament, the Russian Orthodox Church and Russian veterans.

The event will remember hundreds of Russian POWs who died in a snow avalanche in 1916 building the road over the Vršič. The chapel was erected on the site the same year.

Saša Geržina, the head of the Slovenia-Russia Association, said thousands of people were expected for what will also be an event marking the 100th anniversary of the start of WWI.

A piece by the Slovenian composer Ambrož Čopi, "Missa pro pace" (Mass for Peace), which was made specifically for the anniversary, will be performed and interspersed with readings of letters by Russian and Slovenian soldiers who fought in the war.

Sunday's ceremony will be the apex of celebrations which will start in Ljubljana on Friday with a concert of Russian spiritual songs at the St Franciscans' Church and continue on Saturday with a joint parade by Russian and Slovenian soldiers.

Also on Saturday, an ecumenic mass will be held at the Kranjska Gora Church of the Assumption and a St. Peterburg choir will give a concert at the Vitranc Hall.