Facebook has been accused of not cooperating with British police and security services after figures showed that that it turned down one in five emergency requests about social media users.

Numbers from the social media giant showed that in the second half of 2016, it received nearly 1,000 police requests in which there was grounds to believe that the matter involved an "imminent risk of serious physical injury".

The Telegraph reported that it provided information in only 80% of those cases, although this was much higher than the previous six months, in which it rejected 79% of the 731 emergency requests it had received.

Facebook came under fire in March after its WhatsApp site did not co-operate fully with the police after Adrian Ajao sent a message using the service before his terrorist attack in Westminster.

Home secretary Amber Rudd has thrown her weight behind a report by the home affairs select committee calling on social media companies to pay for the policing of digital crimes and face fines if they did not censor illegal posts.

Conservative member of the committee, Tim Loughton, told the Telegraph that the social media company should comply and not "conceal" or "obstruct" if it got a request from police.

"It is bad enough that Facebook have been profiting from advertising revenues when hosting abusive and terrorist promoting postings.

"But they really cannot hid behind freedom of speech exemptions when dealing with clear and serious threats to security and citizens' lives in rebuffing the police and intelligence services," he said.

The paper reported that Facebook would often ask for more information from the police before handing over details about the account holders.

A Facebook spokesman said: "We have clear processes in place for law enforcement to request data from us, including in emergencies.

"In order for us to be able to provide data in these circumstances, law enforcement needs to be able to provide us with sufficient information to locate an account. This is not always possible."