Russia freezes assets of Kremlin critic Navalny's anti-graft group

Russia on Thursday froze the assets of an anti-corruption group that top opposition figure Alexei Navalny set up to expose the questionable wealth of top government officials, his spokeswoman said.

The ruling comes amid a crackdown on the opposition that has seen Navalny jailed and thousands of people detained at a series of rallies in Moscow calling for free and fair elections.

The Foundation for Fighting Corruption (FBK) has published reports detailing the lavish lifestyles of figures close to Russian President Vladimir Putin including Prime Minister Dmitry Medvedev.

A Moscow district court froze 75 million rubles ($1.1 million) held in accounts of the FBK and those of several staff members, Navalny's spokeswoman Kira Yarmysh wrote on Twitter.

"This is the amount that they considered to be 'laundered'," she wrote on Facebook.

Investigators said that the FBK knowingly used a large amount of money that was gained by third parties through crime. A spokeswoman said it was around one billion rubles ($15.3 million).

The foundation solicits donations on its website.

The recent opposition protests have been among the largest since Putin returned to the Kremlin in 2012.

Demonstrators are protesting Moscow's refusal to allow prominent opposition candidates who support Navalny to stand in the Russian capital's September local elections.

Investigators on Thursday also raided the FBK's offices and the homes of lawyers who work for it.

"Right now there are raids and detentions taking place over the 'money-laundering case'," Navalny's aide Leonid Volkov wrote on the foundation's website.

The site posted security camera footage of investigators at the FBK offices accompanied by masked guards on Thursday morning.

Navalny himself is currently serving a 30-day sentence in Moscow for calling for a mass protest. He was taken to hospital from prison with symptoms that officials attributed to an allergic reaction but that his doctor said could be caused by a "toxic agent".

The opposition is planning a large protest in Moscow on Saturday.