LONDON - Russia's Federal Security Service (FSB) said on Tuesday it had opened a criminal case against exiled businessman Mikhail Khodorkovsky and other prominent Kremlin critics, accusing them of plotting to violently seize power.

The FSB said it was investigating all 22 members of the Russian Antiwar Committee - a group of politicians, business people, journalists, lawyers, artists and academics all based outside the country, who oppose Russia's war in Ukraine.