"It looks like G7 lost their solidarity in their attitude to the Russian Federation, which is sad. But the main thing is to keep the solidarity of actions againt Russia. Otherwise, it will be a mega-threat - for Ukraine and the G7, above all", Klimkin wrote.
Previously, French leader Emmanuel Macron assumed Russia could be invited for the next G7 summit as the guest.
U.S. President Donald Trump supported Russia's return to the G7 line-up before the group's summit that took place in Biarritz, France on August 24-26.
President of Ukraine Volodymyr Zelensky claimed that Russia cannot return to G7 until it gives Crimea back to Ukraine and stops military action in Donbas.
Earlier, Steffen Seibert, the press secretary of the German government stated that his country stands against Russia's return to G7. British Prime Minister Boris Johnson shared this view.
Russia was excluded from the G8 club after the annexation of Ukraine's Crimean peninsula in 2014.