Facebook and Twitter are preparing to stand firm against government ministers' calls to ban people from social networks or shut their websites down in times of civil unrest.

The major social networks are expected to offer no concessions when they meet the home secretary, Theresa May, at a Home Office summit on Thursday lunchtime.

Ministers are expected to row back on David Cameron's call for suspected rioters to be banned from social networks, such as Twitter and Facebook, following the riots and looting across England a fortnight ago.

The home secretary will explore what measures the major social networks could take to help contain disorder – including how law enforcement can more effectively use the sites – rather than discuss powers to shut them down. The acting Metropolitan police commissioner, Tim Godwin, and the Tory MP Louise Mensch have separately explored the idea of shutting down websites during emergencies.

The technology companies will strongly warn the government against introducing emergency measures that could usher in a new form of online censorship. Attacks on London landmarks, including the Olympics site and Westfield shopping centres, were thwarted earlier this month after police managed to intercept private BlackBerry Messenger (BBM) posts – suggesting that leaving networks running can provide a valuable source of intelligence and information.

The summit is not expected to signal a dramatic shift in government policy, with only one hour slated for a discussion between more than a dozen social media executives, police officers and ministers.

Executives from Facebook, Twitter and RIM will be joined by Lynn Owens, the assistant commissioner of central operations at the Met police, members of the association of chief police officers, and civil servants from both the foreign office and the department for culture, media and sport. The home secretary will lead the meeting, alongside James Brokenshire, the minister for security and a member of the National Security Council.

May will urge the social networks, all of which are based in either the US or Canada, to take more responsibility for the messages posted on their websites.

In response, Twitter and Facebook are expected to outline the steps that both social networks already take to remove messages that potentially incite violence. Facebook, which has 30 million users in the UK, said it had actively removed "several credible threats of violence" to stem the riots across England this month.

Research in Motion, the Canada-based BlackBerry maker, will explain to the government which parts of its popular BlackBerry Messenger (BBM) service are private or encrypted. Unlike Facebook and Twitter, BBM is a pin-protected instant messaging system, and was claimed to be the most popular network among rioters.

Each of the social networks are preparing to explain how current powers are proportionate for tackling provocative material. Current measures allow internet companies to identify users who may be worth further investigation without examining the content of their messages.

RIM and other companies can be forced to disclose users' private messages if served with a warrant by police.

Godwin told MPs on the home affairs committee last week that police had explored the unprecedented step of switching off social networks, but discovered that they did not have the legal powers to do so.

Under the current system, most websites take down material if served with "notice and takedown procedures" by authorities. Facebook also operates a self-policing method whereby its own users can flag inappropriate material.

Two leading police forces told the Guardian earlier this month that it would be a mistake to introduce overzealous powers over the websites. Greater Manchester police and the Devon and Cornwall force both said social networks had an "overwhelmingly positive" role in dispelling rumours and reassuring residents during the riots.

A spokeswoman for Facebook said: "We look forward to meeting with the home secretary to explain the measures we have been taking to ensure that Facebook is a safe and positive platform for people in the UK at this challenging time.

"In recent days we have ensured any credible threats of violence are removed from Facebook and we have been pleased to see the very positive uses millions of people have been making of our service to let friends and family know they are safe and to strengthen their communities."

Twitter and RIM declined to comment.

Four men from Lancashire appeared in court on Wednesday accused of using Facebook to encourage the looting. None of the four entered pleas to the charges, and all four were granted bail in the hearing at Preston crown court.

Source : guardian