(Reuters) -Slovakia will not back the EU's 18th package of sanctions against Russia unless the European Commission provides a solution to the situation the country faces if the bloc phases out Russian energy as planned, Prime Minister Robert Fico said.

The Commission proposed on Tuesday a new round of sanctions against Russia for its invasion of Ukraine more than three years ago, targeting Moscow's energy revenues, its banks and its military industry.

Fico has criticised separate European Union plans to phase out Russian gas and other energy imports in the coming years, which the EU executive announced last month, calling them "economic suicide".

Hungary, which like Slovakia, continues to rely on Russian gas and oil supplies, and like Slovakia has maintained warm ties with Moscow, has also rejected the plans.

EU countries will start debating the sanctions proposals this week, which require unanimity in the bloc for approval.

"Slovakia will not support the upcoming 18th sanctions package against Russia unless the European Commission provides it with a real solution to the crisis situation that Slovakia will find itself in after the complete cessation of gas, oil and nuclear fuel supplies from Russia," Fico wrote in a Facebook post late on Tuesday.

Slovakia has not blocked any previous sanctions packages.

But Fico had said over the weekend Slovakia would block any sanctions that harmed its national interests.

The Commission's new sanctions package proposes banning transactions with Russia's Nord Stream gas pipelines, as well as banks that engage in sanctions circumvention.

The Commission has also proposed lowering the Group of Seven nations' price cap on Russian crude oil to $45 a barrel, from $60 a barrel, to cut Russia's energy revenues.

Fico has long opposed sanctions against Russia, saying they harmed Slovakia and the EU more than Moscow.

(Reporting by Jason Hovet in PragueEditing by Tomasz Janowski)