MOSCOW—Greek Prime Minister Alexis Tsipras told senior Russian lawmakers here that Athens had played an active role in preventing an expansion of European Union sanctions against Russia earlier this year.

The comments Thursday by Mr. Tsipras, who is in tough talks with European leaders about much-needed international funding, underscored the defiant tone of his two-day trip to Moscow, where he has criticized European sanctions and stressed Russia and Greece’s shared cultural and religious roots.

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