Louise Mensch, the Conservative MP and one of parliament's more active Twitter users, has backed David Cameron's call for social networking services to be shut down temporarily during civil disorder.

Mensch, the MP for Corby and East Northamptonshire and a novelist, used Twitter to call for a "brief temporary shutdown" of Twitter and Facebook to stop unfounded rumours being spread, as she said had occurred in Northamptonshire last week during the riots that spread from London to several cities across England.

"Common sense. If riot info and fear is spreading by Facebook & Twitter, shut them off for an hour or two, then restore. World won't implode," she said.

On her Twitter feed, she added: "Northamptonshire police advise me that much of their time and resources were wasted answering false alarms due to soc media rumours. At the time, tweeted people should think hard before putting the phrase 'rumours of' into a tweet. Nonsense rumours about W'boro [Wellingborough] = 999 calls."

"I don't have a problem with a brief temporary shutdown of social media just as I don't have a problem with a brief road or rail closure. If short, necessary and only used in an emergency, so what. We'd all survive if Twitter shut down for a short while during major riots."

However, Greater Manchester police backed the use of social networks, saying they have allowed authorities to correct rumours before they gather momentum.

Kevin Hoy, web manager at Greater Manchester police, said Twitter allowed them to give "direct reassurance" and "dispel rumours … in a way that we could never have achieved previously".

said Twitter had been an "overwhelmingly positive" and "vital" channel of communication as violence spread across the region. It has urged its 95,000 Twitter followers to "name and shame" suspected rioters in CCTV images it has posted online.

Devon and Cornwall police warned against a kneejerk reaction to claims that Facebook, Twitter and BlackBerry Messenger played a key role in organising disorder across the country.

A force spokesman said: "You have to deal with these things in proportion. Putting someone's door in because of something they posted on Facebook is clearly not proportionate, but speaking to their parents and giving them advice is proportionate. It has the desired effect and we stand by that."

David Cameron said on Thursday the intelligence agencies and police were exploring whether it was "right and possible" to cut off those "plotting violence, disorder and criminality" on social networks. The home secretary, Theresa May, is to hold talks with all major social networks about their responsibility in times of civil unrest.

All three social networks said they would welcome a meeting with May. Facebook said it had boosted its internal team to monitor potentially inflammatory messages and had actively removed several "credible threats of violence" from the website.

But there are questions about whether disconnecting people is necessary and whether or not it is technically feasible.

Police across the country have arrested a number of people accused of organising or inciting violence on social networks.

Devon and Cornwall police made its first arrest on Friday over comments posted by those suspected of inciting violence on social networks. The force has given "words of advice" to eight people, all under 25, over messages posted online.

"If we know they are inciting crime in that way, then we know we can get across to them on the medium that they are using. I would suggest it works because either [inflammatory messages] have been taken down or no disorder has come of them," the spokesman said.

He said Facebook users had taken it upon themselves to "show a sense of social responsibility" and report inflammatory pages this week, resulting in them to be shut down.

Current powers allow police to order mobile phone companies to free up space on their networks for people attempting to call emergency services. However, this is seen as a last resort.

O2 denied accusations that it turned off parts of its network in London during the unrest.