Media playback is unsupported on your device Media caption Blackberry boss Stephen Bates: "Social media were used as a force for good"

Social media were a "force for good" during last month's riots in England, representatives from Blackberry, Facebook and Twitter have told MPs.

Instant messaging and social media providers were linked to the disorder after some rioters used them to arrange meetings and agitate other people.

But Blackberry and Facebook said they had also been used by innocent people to ensure their friends were safe.

Twitter said the prospect of them being shut down was "absolutely horrible".

Some MPs have called for access to social media to be temporarily suspended in the event of a repeat of August's looting and violence but the home secretary has ruled out such action.

The role of social media in the riots came under scrutiny after it emerged that some of those involved had used Blackberry's BBM instant messaging service, part of which is encrypted, to co-ordinate disturbances across London and other cities.

In a separate incident, a man was sentenced to four years in jail for inciting disorder and criminal behaviour through Facebook although he did not take part in any disturbances himself.

However, the police say they prevented attacks by rioters on the Olympic site and London's Oxford Street after picking up intelligence on social networks.

Balance needed

Appearing before the Home Affairs Select Committee - which is looking into the causes and policing of the riots - Blackberry's owner, Research in Motion, acknowledged that its technology had been used for "malicious" purposes.

Police need to develop mechanisms to deal with the social media villain Richard Allan, Facebook

But Stephen Bates, the firm's UK managing director, also insisted the technology had been used positively during the disturbances and the issue had to be seen in a "balanced" way.

"On the whole the vast majority abide by the law and use social media systems as a force for good," he told MPs.

"We saw many instances while the riots were happening where social media were used to check people were safe and they had got to places were they wanted to."

Mr Bates said systems were in place to "protect the privacy" of users of its messaging service - more than a third of which are under 20.

Asked whether the authorities could gain retrospective access to messages, he said the firm complied with "lawful access" requirements under existing legislation governing electronic communications.

Legal responsibility

Facebook said there had been only a "handful of cases" where it was used to organise trouble.

Image caption BlackBerry's BBM requires users authenticate their contacts with a PIN

"Frankly if we had found widespread evidence of this we would have said so but we haven't," Richard Allan, the former Lib Dem MP who is now its director of policy, said.

"Literally we found a handful of cases where people were doing things which were serious organisation as opposed to the good stuff or what you might call joke activity."

Facebook had "a clear responsibility" to ensure its services were not used for illegal behaviour, he said, and suggested the police needed to better understand potential misuse.

"There is clearly a policing issue about catch-up," he added, comparing the use of new technology by criminals to people leaving a crime scene in a car rather than on foot.

"The police took some time to catch up and figure out how to deal with the motorised villain. Now they need to develop mechanisms to deal with the social media villain."

Public forum

Twitter said it had no knowledge of the micro-blogging site being used to incite or co-ordinate disturbances during the recent incidents.

"People come to Twitter to say things publicly and that means there is a different kind of usage," Alexander Macgillivray, the firm's lawyer, said.

It said it had co-operated fully with the police and rejected suggestions that access to it and other social media should be barred if a similar scale of disorder arose in the future.

"We think it would be an absolutely horrible idea to suspend service during important times."

But Keith Vaz, the Labour MP who chairs the committee, said this might be necessary.

"Why should the government not use the powers to close down these networks if there is mass disorder and this is the only way to stop it happening," he argued.

"There may be a set of circumstances or situation, to do with terrorism or high criminality, where they might have to do this."