Police raided the Moscow apartment of incarcerated Russian opposition leader Alexei Navalny on Wednesday, another home where his wife lives, and his anti-corruption organization’s offices.

On social media, Navalny’s aides announced the raids.

If someone had been detained was not immediately apparent. The searches were being carried out for suspected epidemiological or welfare abuses, said Leonid Volkov, director of Navalny’s corruption-investigating agency.

Police also investigated Navalny’s spokeswoman’s flat, who was detained and jailed last week, and an investigator for Navalny’s party, the organization stated.

The searches are arriving in the middle of increasing tensions over Navalny. Last weekend, rallies demanding his release were organized nationwide in Russia. Nearly 4,000 protesters were officially arrested in the protests by the police. His supporters have called for more Sunday protests to take place.

Navalny was arrested on Jan. 17 after returning from Germany to Russia, where he had spent five months suffering from the poisoning of a nerve agent he blamed on the Kremlin. In the poisoning, the Russian government denies complicity.

When onboard a domestic flight from Siberia to Moscow on Aug. 20, Navalny, the most famous and enduring opponent of the Kremlin, collapsed into a coma. Two days later, he was moved from a hospital in Siberia to a Berlin hospital. Labs in Germany, France and Sweden, and experiments performed by the Chemical Weapons Prohibition Agency, confirmed that he was subjected to the Novichok nerve agent of the Soviet period.

The Russian authorities declined to launch a full-fledged criminal investigation, citing a lack of proof that Navalny had been poisoned.

Navalny released a recording in December of a phone call he said he made to a man he identified as a suspected member of a Federal Security Service (FSB) group of officers who allegedly poisoned him in August and then attempted to cover it up. The recording was rejected by the FSB as fraudulent.

The detention of Navalny and the brutal police conduct during the demonstrations have brought strong Western condemnation and demands for his release.

A resolution by the Coalition of Seven Foreign Ministers condemning his detention, Russia’s Foreign Ministry said Wednesday, constituted “gross interference” in Russia’s domestic relations.