Governments around the world condemned mass crackdowns in Russia in the wake of protests following the arrest of activist Alexei Navalny only days after his return from Germany.

Observers estimate more than 3,500 Navalny supporters were detained over the weekend after a rash of street demonstrations in nearly 100 cities across the country.

The arrests are "a slide toward authoritarianism," French Foreign Minister Jean-Yves Le Drian said Sunday. "Russia is our neighbor and we must find a way for discussions to take place.

The nationwide protests were sparked by Navalny's arrest after he returned to Russia last weekend for the first time in nearly six months. The outspoken democracy activist and politician sought treatment in August for what many believe was an assassination attempt with the deadly Soviet nerve agent Novichok.

His stay in Germany was in breach of parole conditions relating to a 2014 fraud and embezzlement conviction, according to Russian authorities who took Navalny into custody after he stepped off the plane.

These are "trumped up charges" according to the activist, who accused the Russian government of muzzling dissent.

"The U.S. supports the right of all people to peaceful protest, freedom of expression. Steps being taken by Russian authorities are suppressing these rights," Rebecca Ros, an official at the American embassy in Moscow, said Saturday.

Russians angry with Putin's dictatorship in everything but name organized protests from Siberia to St Petersburg that soon turned violent, as video recordings of Moscow police beating and dragging away demonstrators show.

"This is a professionally prepared provocation, encouraged by embassies of Western countries, including [the] US Embassy in Moscow," a representative for the Russian Embassy in Britain said.

International law must be observed if Russia wishes to avoid further conflicts, Polish leader Andrzej Duda told the Financial Times. "The only way to do this without rifles, cannons and bombs is via sanctions," he said.

Echoing Duda, the Baltic states' foreign ministers demanded "restrictive measures against Russian officials responsible for [the] arrests" in a joint statement.

But not all foreign governments condemned the arrests, with China backing the beleaguered Putin administration.

"We support Russia in its actions to maintain security and stability as this serves the interests of the Russian people," Chinese Foreign Ministry representative Hua Chunying said Friday.