RUSSIAN stocks tumbled in their biggest decline in over four years amid concern the arrest on Saturday of Mikhail Khodorkovsky, chief executive of AO Yukos Oil Co and the country’s richest man, may scare off investors.

The jailing of Russia’s richest man in what is widely seen as a politically-driven attack on his oil empire could herald a return to Soviet-style repression that is bound to trigger capital flight, media and politicians warned today.