Russian state investigators have brought new charges against opposition leader Alexei Navalny.

They say Mr Navalny, who is convalescing in Germany after being poisoned, fraudulently spent public donations on his personal needs.

Mr Navalny described the case as a fabrication and "hysterics" from President Vladimir Putin.

The Kremlin has repeatedly denied Mr Navalny's claims the president was behind the near-fatal attack in August.

A report published by investigative group Bellingcat and Western media earlier this month blamed FSB agents for the poisoning, carried out with the nerve agent Novichok.

The new charges come days after Navalny ally Lyubov Sobol was detained in Moscow after an early-morning raid on her home.

She is suspected of threatening a Federal Security Service (FSB) agent, who Mr Navalny says was involved in poisoning him.

Last week, Mr Navalny posted a recording of a 45-minute conversation with the agent, Konstantin Kudryavtsev, on his YouTube channel, in which he apparently tricked him into divulging details of the attempt on his life.

The video has been viewed more than 21 million times.

'Putin is a thief'

Russia's Investigative Committee, which deals with serious crimes, accuses Mr Navalny of spending more than $4.8m (£3.55m) of public donations to his organisations on personal acquisitions.

It says he used the funds to acquire property, buy material goods and pay for expenses such as overseas travel.

Mr Navalny responded on Twitter that he had expected a reaction of this kind.

"I always said they would try to put me in jail for surviving and then hunting my killers. For proving that Putin is personally behind it all, " he said.

"He is a thief who is ready to kill those who refuse to keep quiet about his thievery."

Analysts say the charges are likely to be seen as a sign that the Russian authorities do not want Mr Navalny to return to Russia, though their official position is that he is free to return.

On Monday he said the Russian prison service had ordered him to return to Russia by Tuesday or face a possible prison sentence in a separate theft case. He currently has a suspended sentence in the case.

The opposition leader says he intends to go back to Russia when he is recovered, but was unable to return for this deadline.