
Superintendent David Hartshorn, who heads the Metropolitan Police's public order branch, said he feared there could be "mass protest" at rising unemployment, failing financial institutions and the downturn in the economy.
He said that "known activists" were planning returns to the streets, and intelligence revealed that they may be able to call on more protesters than normal due to the unprecedented conditions.
He said: "Those people would be good at motivating people, but they haven't had the 'footsoldiers' to actually carry out (protests).
"Obviously the downturn in the economy, unemployment, repossessions, changes that. Suddenly there is the opportunity for people to mass protest."
Supt Hartshorn, who is regularly briefed on potential causes of civil unrest, singled out April's G20 summit of the leading developed nations in London as one of the events that could kick start a series of protests.
"We've got G20 coming and I think that is being advertised on some of the sites as the highlight of what they see as a 'summer of rage'," he said.
The officer added that banks, particularly those that still pay large bonuses despite receiving billions of aid from the taxpayer, has also become "viable targets" for protesters.
Other parts of Europe have already seen large-scale protests against the handling of the economy.
Up to 120,000 people marched through Dublin on Saturday in an emotional and angry national demonstration over the Irish Government's handling of the economic crisis.
In the UK earlier this month, hundreds of oil refinery and power station workers carried out a series of wildcat strikes over the use of foreign workers.
And across the Channel in France, a million people joined demonstrations to demand greater protection for jobs.
i might have to move back to london!