Russia is planning attacks on critical infrastructure in the Baltic states or Poland, the Lithuanian and Latvian presidents warned on Wednesday, citing intelligence reports.

"We are talking about energy and transport infrastructure, facilities where damage could... disrupt the functioning of the entire energy system," Lithuanian President Gitanas Nauseda said at a joint press conference in Vilnius with his Latvian counterpart, Edgars Rinkevics.

"This planning is taking place at the highest level, practically in Moscow," he added.

Rinkėvics warned that Estonia, Latvia, Lithuania and Poland, all members of the EU and NATO, should be prepared for provocative actions by Russia as it seeks to "test" the alliance's mutual defense pact amid its war in Ukraine.

"Even without a complete Ukrainian victory, Russia could indirectly test Article 5 and response mechanisms at the alliance and European Union levels," he said.

In late June, Polish Prime Minister Donald Tusk said at a press conference that "various types of escalation can be expected in the coming weeks and months," calling the situation "very unstable."

Officials in the Baltic states and Poland have already linked Russia to several incidents, including deliberate arson, cyberattacks and diversions on railway lines.

The Lithuanian president said his country had strengthened the protection of transport and energy infrastructure in response to threats.

Kremlin spokesman Dmitry Peskov denied the claims.

"This is just another new batch of scare stories designed to continue the brainwashing and prepare the population for further militarization," he said.

Located along the Baltic Sea and bordering Russia and its close ally, Belarus, Lithuania has been a key ally of Ukraine since the start of the full-scale invasion in 2022.

Lithuania is the highest security spender in NATO in relative terms, allocating 5.33% of its GDP to defense.