Covert Russian cyber attacks against Western countries could cause civilian fatalities and potentially escalate into a real-world military confrontation, Latvia's foreign minister has warned.

Edgars Rinkevics says that Russia may use a massive war game this month to probe Nato's resilience to full-spectrum "hybrid" warfare including propaganda and cyber attacks that Moscow has previously used against Ukraine.

A Russian Orthodox priest blesses paratroopers during celebrations of Paratroopers Day in the Red Square in Moscow. Credit:AP

And he warned that deaths from deniable cyber attacks designed to test the "resilience and resolve" of the West by hitting key infrastructure like power grids could start a dangerous cycle of retaliation.

"What I am rather worried about is that this hidden cyber warfare can escalate to a level of cyber warfare where we are not going to talk about bank attacks or ransom payments," he said.