Poland’s president Andrzej Duda has urged the EU to step up its sanctions on Russia in the wake of the summary arrest and jailing of Alexei Navalny, the anti-corruption activist who has become Vladimir Putin’s most prominent critic.

EU foreign ministers are due to discuss their response on Monday, and Mr Duda said talk of further sanctions was “absolutely justified” given both the treatment of Mr Navalny, and Russia’s continued involvement in unresolved conflicts in both Georgia and Ukraine, where it annexed Crimea in 2014. He said the EU’s high representative for foreign affairs, Josep Borrell, should also reconsider plans to visit Moscow next month.

“There is no other peaceful tool for applying pressure to a state that breaks the rules of international law. The primacy of international law is fundamental here. As long as international law is observed, there is no war. If international law is broken, the effect of this is always conflict,” Mr Duda told the Financial Times.

“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.”

Protests flared across Russia on Saturday after Mr Navalny was detained on his return from Germany last week, where he was being treated after surviving an assassination attempt involving the Soviet-developed nerve agent novichok last year. More than 2,000 demonstrators were arrested during an often violent crackdown by Russian security services.

The US state department condemned the “harsh tactics” used by the authorities. On Sunday, Dmitry Peskov, Mr Putin’s spokesman, attacked the American embassy in Moscow for publishing details of the protests in major cities, in a notice that warned US citizens to avoid them. Such actions, he said, were “indirectly, an absolute interference in our internal affairs”.

Mr Peskov also played down the scale of the protests. “Many are saying that a lot of people took part in illegal actions. No, only a few people came out; many people vote for Putin,” he said. “If you compare the numbers, you will understand how few these people are,” he told a weekly state television programme dedicated to Mr Putin’s life.

Mr Duda said targeting Russia’s state-run gas giant Gazprom would be one way of ratcheting up the pressure on the Kremlin. “I think that if we limit the possibility of Gazprom functioning economically on the territory of the EU, especially by concluding new investments, then things including respect for international law and for human and political rights in Russia would start moving forward, because that would be a serious move in the domain of Russian economic interests,” he said.

While some other EU countries, notably the three Baltic states, share Poland’s hawkish stance, the bloc is deeply divided on policy towards the Kremlin. But the clampdown on protesters has raised the stakes of the foreign ministers’ talks on Monday.

The EU has already imposed sanctions on six top Russian officials over their alleged involvement in Mr Navalny’s poisoning. While the bloc could move towards further targeted sanctions on individuals and institutions, more sweeping economic countermeasures — such as those imposed after Moscow’s annexation of Crimea — are likely to be contentious.

Nonetheless, Mr Duda said Mr Borrell’s planned visit to Moscow next month would be a mistake unless “the condition of his visit would be the release of Mr Navalny”.

“Without that, I don’t think there is anything to speak about,” he said.

“Russia is not a country which you can trust, or which shares the same values and goals from the point of view of the rules of democracy as Euro-Atlantic states. It is a different country. It is a country that has been showing for years that its imperial ambitions have returned.”

Poland has long regarded close ties with the US as a crucial part of its defence against a resurgent Kremlin. During the presidency of Donald Trump, with whom Mr Duda forged close relations, Warsaw signed deals for billions of dollars of US military kit. Mr Trump also pledged to move an additional 1,000 troops and the forward command of the US Fifth Corps to Poland.

Initial relations with the Biden administration have been less effusive, however. During his election campaign, Mr Biden mentioned Poland — which is at loggerheads with the EU over judicial changes that Brussels says undermine the rule of law — in the same breath as Belarus and the “rise of totalitarian regimes in the world”. Unlike other European leaders, Mr Duda did not congratulate Mr Biden on his victory until it was confirmed by the electoral college, six weeks after the election.

Mr Duda downplayed both events, arguing that relations between Warsaw and Washington were “too important” to be made dependent on a single “remark or gesture”, and that it would have been “premature” to issue congratulations on the basis of media decisions to call the results.

Instead, he said that he hoped that the close relations between the US and Poland would continue under the new administration, and that Mr Biden would continue Mr Trump’s policy of engagement with central Europe.

Mr Duda pointed out that under Barack Obama — a Democrat, like Mr Biden — the US had bolstered its military presence in Poland, and said that he would “strive” to persuade his new US counterpart to boost the American military contingent in Poland again, arguing that this would be “in the interest of the Nato alliance”.

“I would be happy if [the US presence] was further increased, and I would be happy if the US army moved even more of its infrastructure to Poland than it has up to this point,” he said. “We are prepared to receive the US army here and create the necessary conditions for it to be stationed.”

Additional reporting by Michael Peel in Brussels