The Lindsey Oil Refinery foreign labour row spread across the UK
Police are preparing to face a "summer of rage" in the UK as people join protests over the economic downturn, says a senior Met Police officer.
"Known activists" were likely to foment unrest, with the recession creating more "footsoldiers" to join them, Supt David Hartshorn told the Guardian.
The G20 meeting in London in April is expected to be a focus of protests.
BBC home editor Mark Easton said signs of anger would "not necessarily translate into action on the streets".
Supt Hartshorn is regularly briefed on potential civil unrest, as head of Scotland Yard's public order branch.
The officer said that the established activists "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."
He added: "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'."
The G20 meeting will bring together leading industrial powers and emerging market nations.
Supt Hartshorn also said that banks, particularly those that paid large bonuses despite receiving billions of pounds of taxpayers' money, had become "viable targets" for protesters.
But our home editor said "activity on websites does not necessarily translate into action on the streets".
"With the entire economy at grave risk, it is unclear whether anger at the failures of banks, other financial institutions and governments will translate into support for action designed to topple those same bodies."
He added: "That police have identified attempts to exploit the current economic downturn is not a surprise and they will undoubtedly be arguing for greater resources to counter a potential threat to public order."
The year has already seen wildcat strikes across the UK in sympathy with British workers protesting at the use of foreign labour at Lindsey Oil Refinery in Lincolnshire.
On Saturday, about 100,000 joined a march in Dublin to protest about the Irish government's handling of the country's recession.
Greece, France and Iceland have also seen protests over the economic crisis.