Anti-Yeltsin protesters and police fought hand to hand with bricks, metal rods and rubber truncheons in the most serious civil disturbance since the failed coup of August 1991.
About 1,500 of the protesters began building barricades around the building. Declaring that a 'patriotic war' had begun, they vowed to hold a vigil until a special session of the legislature was called to remove Mr Yeltsin from office.
Ironically, it was in front of this building that Mr Yeltsin stood on a tank to defy the 1991 coup by hardliners.
'I'm here to stay, where else should I go?' demanded Igor Kalinin, a factory worker and self-styled Bolshevik who had a bloody bandage around his head as a result, he said, of being hit by a truncheon- wielding policeman.
Riot police had turned their batons and water cannon on marchers after they made a violent attempt to reach Red Square in defiance of Mr Yeltsin's ban on May Day demonstrations next to the Kremlin.
Chanting 'Death to Yeltsin', the Communists set fire to two police trucks which were blocking their way and tore chunks of masonry from the entrance of an underground station to hurl at the officers. Initial reports said one policeman had been killed, although this could not be confirmed. Dozens of police and protesters were injured.
May Day was once a predictable Communist festival during which thousands of 'volunteers', waving balloons and paper flowers, marched past Kremlin leaders in Red Square. This year it always seemed likely to be rough, in the tense atmosphere following Mr Yeltsin's referendum victory, which the opposition refuses to recognise.
In an attempt to avoid unrest, the President decreed that Red Square itself was off-limits for political meetings although the Mayor of Moscow, Yuri Luzhkov, said the Communists were free to gather at Krymsky Val near Gorky Park.
But the demonstrators, led by the extremist National Salvation Front, said they would pay no attention to the 'provocative' decrees of Mr Yeltsin and Mr Luzhkov.
The protesters, numbering about 2,000, first gathered in October Square, carrying red Soviet flags and placards alleging the referendum was rigged. Beneath an enormous statue of Lenin, which still stands despite the collapse of Communism, they listened to speeches about how Mr Yeltsin had betrayed Russia. Then they tried to move towards the centre of the city. A large detachment of riot police, all with shields and some on horseback, held them at bay.
The angry demonstrators turned their backs on the centre and set off, their numbers swelling to about 5,000 as they went, towards the Vorobyov (formerly Lenin) Hills near the university. But the police stopped them again, this time at Gagarin Square where, under the shiny metallic statue of the first man in space, a pitched battle broke out. Witnesses said about 200 Communist ringleaders attacked the police with the poles from their flags and set fire to police trucks and private cars. A voice over the loudspeaker of the van which led the Communists asked for volunteers who knew anything about explosives.Reuse content