The decision comes amid continued political uncertainty and scepticism over whether Boris Yeltsin will last much longer in the Kremlin following his latest heart attack.
Doctors said the 64-year-old President's condition remained unchanged yesterday, three days after he was admitted to hospital for the second time within four months. Although his aides insist he remains in control of his administration, even his advisers have reportedly been barred from seeing him - fuelling speculation that his condition is worse than his inner circle is willing to admit.
Yabloko is led by Grigory Yavlinsky, an economist and politician who is considered popular. Yesterday the party was banned by the Central Electoral Commission, the body policing the election on 17 December, on the grounds that it had broken the rules by dropping at least six candidates from its list against their wishes.
This is a blow to Mr Yavlinsky, who is seen as a possible candidate in the Russian presidential elections next June. But it may not grieve the other liberal parties vying for seats in an election seen as a crucial test of Russian public opinion before the presidential race.
Earlier this month, the commission caused a scandal by releasing the names of 85 candidates who allegedly have criminal convictions. It later transpired that the list included genuine ex-convicts and political dissidents.