The museum will serve as a "permanent memory of those who gave their lives for peace, liberty and prosperity of future generations," Russian Foreign Minister Sergey Lavrov said.

During the war the Russian prisoners, up to 5,000 at a time, were housed in warehouses in Melje borough in what was dubbed Camp Stalag XVIII D.

It is believed thousands perished due to famine and disease, according to Aleksandra Berberih Slana, director of the Maribor Museum of National Liberation.

The abandoned warehouses are now empty and will be converted into a museum, with today's ceremony marking the symbolic launch of restoration and construction works.

Lavrov said the centennial of the start of WWI and next year's 70th anniversary of the end of WWII were an opportunity to "remember the victims and the disastrous consequences of these two horrible wars".

The museum should serve as a warning to humanity "to not allow the revival of Fascism and Nazism in Europe or anywhere else", said Lavrov, one of the main speakers at the event.

Slovenian Foreign Minister Karl Erjavec added it was important to "preserve the memory of the contribution of each individual" who helped make it possible that Europe is now peaceful, free and safe.

"We must all strive not to jeopardise that with our actions," he said.

The ceremony features high-profile guests including two former Slovenian presidents, Milan Kučan and Danilo Türk, several Slovenian cabinet members and Russian Minister of Communication and Mass Media Nikolai Nikiforov.