Police are preparing for a "summer of rage" as victims of the economic downturn take to the streets to demonstrate against financial institutions, the Guardian has learned.

Britain's most senior police officer with responsibility for public order raised the spectre of a return of the riots of the 1980s, with people who have lost their jobs, homes or savings becoming "footsoldiers" in a wave of potentially violent mass protests.

Superintendent David Hartshorn, who heads the Metropolitan police's public order branch, told the Guardian that middle-class individuals who would never have considered joining demonstrations may now seek to vent their anger through protests this year.

He said that banks, particularly those that still pay large bonuses despite receiving billions in taxpayer money, had become "viable targets". So too had the headquarters of multinational companies and other financial institutions in the City which are being blamed for the financial crisis.

Hartshorn, who receives regular intelligence briefings on potential causes of civil unrest, said the mood at some demonstrations had changed recently, with activists increasingly "intent on coming on to the streets to create public disorder".

The warning comes in the wake of often violent protests against the handling of the economy across Europe. In recent weeks Greek farmers have blocked roads over falling agricultural prices, a million workers in France joined demonstrations to demand greater protection for jobs and wages and Icelandic demonstrators have clashed with police in Reykjavik.

In the UK hundreds of oil refinery workers mounted wildcat strikes last month over the use of foreign workers.

Intelligence reports suggest that "known activists" are also returning to the streets, and police claim they will foment unrest. "Those people would be good at motivating people, but they haven't had the 'footsoldiers' to actually carry out [protests]," Hartshorn said. "Obviously the downturn in the economy, unemployment, repossessions, changes that. Suddenly there is the opportunity for people to mass protest.

"It means that where we would possibly look at certain events and say, 'yes there'll be a lot of people there, there'll be a lot of banner waving, but generally it will be peaceful', [now] we have to make sure these elements don't come out and hijack that event and turn that into disorder."

Hartshorn identified April's G20 meeting of the group of leading and developing nations in London as an event that could kick-start a challenging summer. "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.

His comments are likely to be met with disappointment by protest groups, who in recent weeks have complained that police are adopting a more confrontational approach at demonstrations. Officers have been accused of exaggerating the threat posed by activists to justify the use of resources spent on them.

Police were said to have been heavy-handed at Greek solidarity marches in London in December and, last month, at protests against Israel's invasion of Gaza. In August 1,000 officers, helicopters and riot horses were drafted to Kent from 26 UK police forces to oversee the climate camp demonstration against the Kingsnorth power station. The massive operation to monitor the protesters cost £5.9m and resulted in 100 arrests. But in December the government was forced to apologise to parliament after the Guardian revealed that its claims that 70 officers had been hurt in violent clashes were wrong.

However, Hartshorn insisted: "Potentially there will be more industrial actions ... History shows that some of those disputes - Wapping, the miners' strike - have caused great tensions in the community and the police have had difficult times policing and maintaining law and order."

Both "extreme rightwing and extreme leftwing" elements are looking to "use the fact that people are out of jobs" to galvanise support, he said.

A particularly worrying development was the re-emergence of individuals involved in the violent fascist organisation Combat 18, he said. "They are using the fact that there's been lots of talk about eastern European people coming in and taking jobs on the Olympic sites," he said. "They're using those type of arguments to look at getting support."

Hartshorn said he also expected large-scale demonstrations this year on environmental issues, with hardcore green activists "joining forces" with middle-class campaigners over issues such as airport expansion at Heathrow and Stansted. With the prospect of angry demonstrations against the economy, that could open the door to powerful coalitions.

"All you've got to do then is link in with the environmentalists, and look at the oil companies. They're seen to be turning over billions of pounds profit in issues that are seen to be against the environment."