MOSCOW – Aleksei A. Navalny, the Russian opposition leader who has been recovering in Germany for months from a nerve agent attack widely believed to be carried out by the Russian state, said on Wednesday that he would return to prison on arrival this weekend despite the threat from Russia will.

Mr Navalny said on social media posts that he bought a ticket for a flight to Moscow that Sunday. His announcement that he would return came just two days after the Russian prison authorities petitioned a court to detain Mr. Navalny for violating a previous suspended sentence.

“You are doing everything to scare me,” Navalny said in an Instagram post on Wednesday, referring to the Russian authorities. “But I don’t care what you do. Russia is my country, Moscow is my city and I miss it. “

Mr Navalny was poisoned by a military-grade nerve agent in Siberia in August. He and Western officials said this was an assassination attempt by the Russian government. He fell into a coma and was flown to Berlin for treatment.

He said on Wednesday that he now believes he is well enough to return to Russia. He bought tickets from the low-cost airline Pobeda and planned to return to Moscow on Sunday.

“Come meet me!” he said.