BERLIN – Alexei Navalny, Russia's most prominent opposition leader, who was poisoned in August in Siberia, says he has no doubt that President Vladimir Putin was behind the attack.

In his first full interview since being released from the hospital, Navalny said the use of a closely held, military-grade nerve agent in the attack was convincing evidence that it had been ordered at the highest level of Russia's security or intelligence services.

"Putin is behind the crime," he told German newsmagazine Der Spiegel in an interview published Thursday.

Navalny has been recuperating in a Berlin hospital since he was flown to Germany after the poisoning. Although he became ill and collapsed on a domestic flight in Russia, he and his team believe he was poisoned in his hotel room in Omsk, Siberia. He was discharged from a German hospital last week after 32 days, many of them in a medically induced coma.

Initially, Navalny was treated for two days at a hospital in Russia, where doctors offered a variety of diagnoses — none of them poisoning with a nerve agent from the Novichok family, as German military investigators determined — and claimed he was too sick to be moved.

The opposition leader called that a ruse and said the Russians had initially been determined not to let him leave the country. "They were waiting for me to die," he said.

Moscow has maintained that it played no role in the poisoning.

The Novichok family of nerve agents was developed in the Soviet Union and Russia in the 1980s and '90s, and can be delivered as a liquid, powder or aerosol. The chemical is said to be more lethal than other well-known nerve agents.

"The doctors say I can recover 90%, maybe even 100%, but nobody really knows," he said. "Basically, I'm something of a guinea pig — there aren't that many people you can watch living after being poisoned with a nerve agent."

Navalny said he intended to return to Russia as soon as his health improves, because not returning would signal a victory for Putin. He also vowed to continue traveling throughout Russia and staying in hotels, despite fears for his life. "My task now is to remain the guy who is not afraid," Navalny said. "And I am not afraid!"