MOSCOW -- Russian authorities have banned the British-based organization Open Russia, which is a strong critic of the Kremlin, but the group's Russia branch claims it is administratively separate and can continue to operate.

Open Russia has called for a protest Sunday against President Vladimir Putin and the Russian branch claims it will go ahead.

The group said "see you on April 29" on its website Wednesday after the Prosecutor-General's office announced ban, which also applied to the US-based Institute of Modern Russia.

Open Russia was started by Mikhail Khodorkovsky, the former oil tycoon whose political ambitions angered the Kremlin. Khodorkovsky was imprisoned for 10 years, then pardoned in 2013 and left the country.

The prosecutor's office said the organizations aimed at inspiring protests and destabilizing the country.