In this Feb 29, 2020 photo, Russian opposition leader Alexei Navalny takes part in a march in memory of murdered Kremlin critic Boris Nemtsov in downtown Moscow. (KIRILL KUDRYAVTSEV / AFP)

MOSCOW - Russian prosecutors said on Thursday they saw no need for a criminal investigation into the sudden illness of Kremlin critic Alexei Navalny, who his supporters suspect was poisoned, and they had found no sign that any crime had been committed.

The Interior Ministry said it had started a preliminary investigation into the case, but this was routine

The Interior Ministry said it had started a preliminary investigation into the case, but this was routine.

Kremlin spokesman Dmitry Peskov reiterated the government’s position that there was no need for a formal investigation but that preliminary checks were always carried out in such situations.

Navalny, 44, was airlifted to Germany on Saturday after collapsing during a flight from the Siberian city of Tomsk to Moscow. He is now in a medically-induced coma in a Berlin hospital.

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The hospital said its initial medical examination pointed to poisoning, though Russian doctors who had treated Navalny in a Siberian hospital have contradicted that diagnosis.

On Thursday, the Russian Prosecutor General’s office said there was no indication a crime had been committed against him.

It saw no basis to open a criminal investigation, the office said in a statement.

German authorities have agreed to cooperate with Russia on the case, the Prosecutor General’s office said, asking Germany to share information about his treatment and promising to give some back in exchange.