Polish President Andrzej Duda has called for the European Union to step up sanctions against Russia following the detention of Kremlin critic Alexei Navalny, the Financial Times reported on Sunday.

"The only way to (avoid conflict) is to force international law to be observed. The only way to do this without rifles, cannons and bombs is via sanctions. So we are ready to help build consensus on that issue," Duda told the FT.

Duda also said that the EU's foreign affairs chief Josep Borrell should re-consider plans to visit Russia next month unless Navalny is released.

EU foreign ministers are due to discuss their response to Navalny's detention on Monday, following demonstrations across Russia over the weekend at which some 3,500 protesters were arrested.

Foreign ministers of the three Baltic states on Saturday said they wanted "restrictive measures against Russian officials responsible for arrests".

Navalny, 44, rose to prominence a decade ago and has become the central figure of Russia's opposition movement, leading large-scale street protests against corruption and electoral fraud.

He survived a near-fatal poisoning with the Novichok nerve agent and returned to Moscow earlier this month following months of treatment and recovery in Germany.

His arrest and detention upon arrival in Moscow drew widespread Western condemnation, with the United States and the European Union calling for his release.

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