Widespread anger and frustration at the way police engage with communities was a significant cause of the summer riots in every major city where disorder took place, the biggest study into their cause has found.

Hundreds of interviews with people who took part in the disturbances which spread across England in August revealed deep-seated and sometimes visceral antipathy towards police.

In a unique collaboration, the Guardian and London School of Economics (LSE) interviewed 270 people who rioted in London, Birmingham, Liverpool, Nottingham, Manchester and Salford.

The project collected more than 1.3m words of first-person accounts from rioters, giving an unprecedented insight into what drove people to participate in England's most serious bout of civil unrest in a generation. Rioters revealed that a complex mix of grievances brought them on to the streets but analysts appointed by the LSE identified distrust and antipathy toward police as a key driving force.

Details of the research findings, which are also based on an analysis of an exclusive database of more than 2.5m riot-related tweets, will be unveiled in a series of reports over the next five days. Monday's findings include:

• Many rioters conceded that their involvement in looting was simply down to opportunism, saying that a perceived suspension of normal rules presented them with an opportunity to acquire goods and luxury items they could not ordinarily afford. They often described the riots as a chance to obtain "free stuff" or sought to justify the theft.

• Despite David Cameron saying gangs were "at the heart" of the disturbances, evidence shows they temporarily suspended hostilities. The effective four-day truce – which many said was unprecedented – applied to towns and cities across England. However, on the whole, the research found gang members played only a marginal role in the riots.

• Contrary to widespread speculation that rioters used social media to organise themselves and share "viral" information, sites such as Facebook and Twitter were not used in any significant way. However, BlackBerry phones – and the free messaging service known as "BBM" – were used extensively to communicate, share information and plan riots in advance.

• Although mainly young and male, those involved in the riots came from a cross-section of local communities. Just under half of those interviewed in the study were students. Of those who were not in education and were of working age, 59% were unemployed. Although half of those interviewed were black, people who took part in the disorder did not consider these "race riots".

• Rioters identified a range of political grievances, but at the heart of their complaints was a pervasive sense of injustice. For some this was economic: the lack of money, jobs or opportunity. For others it was more broadly social: how they felt they were treated compared with others. Many mentioned the increase in student tuition fees and the scrapping of the education maintenance allowance.

Although rioters expressed a mix of opinions about the disorder, many of those involved said they felt like they were participating in explicitly anti-police riots. They cited "policing" as the most significant cause of the riots, and anger over the police shooting of Mark Duggan, which triggered initial disturbances in Tottenham, was repeatedly mentioned – even outside London.

For the research, funded by the Joseph Rowntree Foundation and Open Society Foundations, a team of more than 60 academics, researchers and journalists spent three months interviewing people rioters and analysing their accounts.

The most common complaints related to people's everyday experience of policing, with many expressing deep frustration at the way people in their communities were subjected to stop and search. An independent panel set up by the government in the aftermath of the riots identified stop and search as a possible "motivation factor" for black and Asian rioters.

In findings released last week, the panel – which took evidence from riot-hit communities and victims, but did not speak to rioters – concluded there was no single cause for the riots, but urged police to improve the way stop and search is conducted. "Where young law-abiding people are repeatedly targeted there is a very real danger that stop and search will have a corrosive effect on their relationship with the police," it said.Of those interviewed in the Reading the Riots study, 73% said they had been stopped and searched in the previous 12 months. They were more than eight times more likely to have been stopped and searched in the previous year than the general population in London.

The Metropolitan police's internal report on the riots, also released last week, appeared to identify simmering tensions with police. Citing community feedback about the riots, the report concluded: "Either the violence was spontaneous without any degree of forethought or … a level of tension existed among sections of the community that was not identified through the community engagement."

The Met said it welcomed the research that provides an insight into why the riots occured "so that police and society can do everything possible to prevent a recurrence".

"We will consider this research alongside the detailed operational review that we are conducting." The force said its own research showed 66% of Londoners believed the MPS does a good job in their area, and that stop and search "can be a highly effective and essential tactic" against knife crime.

It added: "Stop and search will continue to be necessary but we want to ensure that it is only used in an intelligent, professional, objective and courteous way."

The second phase of Reading the Riots, to be completed next year, will draw on interviews with communities, police and judges about their experience of the disturbances and their aftermath.