Riot police staged baton charges to try to disperse several hundred protesters gathered around the Bank of England in the heart of London's financial center on Wednesday after a day of protest against the G20 summit.
Demonstrators had earlier attacked a nearby branch of Royal Bank of Scotland in protest against a system they said had robbed the poor to benefit the rich. Hundreds of protesters converged on the bank, shattering three windows.
Rescued by the government in October, RBS and former boss Fred Goodwin, who controversially refused to give up a pension award of 700,000 ($1 million), became lightning rods for public anger in Britain over banker excess blamed for the crisis.
The protests were timed to coincide with a G20 meeting of the world's leading and emerging economies.
Protesters hurled paint bombs and bottles, chanting: Our streets! Our banks!
RBS said in a statement it was aware of the violence outside its branch and had already taken the precautionary step of closing central city of London branches.
As dusk fell, police charged against a hard core of anti-capitalist demonstrators in an attempt to disperse them before nightfall. Bottles flew through the air toward police lines and police on horseback stood by ready to intervene.
Some protesters set fire to an effigy of a banker hanging from a lamppost.
Police brought out dogs as they tried to channel the few hundred remaining protesters through the narrow streets surrounding the classical, stone-clad Bank of England.
Police said 32 protesters had been arrested by early evening and at least one officer was taken to hospital for treatment.
Some 4,000 protesters had thronged outside the central bank, and a Gucci store nearby was closed and its windows emptied.
Demonstrations were planned for Thursday at the venue in east London where world leaders will discuss plans to fight the financial crisis, police said.
HORSEMEN OF THE APOCALYPSE
Earlier, protesters marched behind models of the four horsemen of the apocalypse representing financial crimes, war, climate change and homelessness.
Some threw eggs at police and chanted build a bonfire, put the bankers on the top. Others shouted jump and shame on you at financial sector workers watching the march from office block windows.
I am angry at the hubris of the government, the hubris of the bankers, said Jean Noble, a 60-year-old from Blackburn in northern England.
I am here on behalf of the poor, those who are not going to now get their pension or who have lost their houses while these fat cats keep their bonuses, hide their money in tax havens and go and live where nobody can touch them.
A smaller demonstration against Britain's military role in Iraq and Afghanistan attracted several hundred people in Trafalgar Square, not far from parliament.
The protests, which brought together anti-capitalists, environmentalists, anti-war campaigners and others, were meant to mark what demonstrators called Financial Fools' Day -- a reference to April fool's day which falls on April 1.
Police stopped a military-style armored vehicle with the word RIOT printed on the front and a police spokesman said its 11 occupants were arrested for having fake police uniforms.
(Additional reporting by William Maclean; Writing by Peter Griffiths) .