Facebook’s plans to implement end-to-end encryption on all its messaging products will lead to continued exploitation of some of the British children it would otherwise help to safeguard, the company has admitted to a House of Commons committee. The firm operates a number of programmes to find and prevent child exploitation on its platforms, from scanning private messages to acting on referrals from law enforcement and other social media sites. Between them, according to evidence submitted to the home affairs committee, these programmes report around 3,000 at-risk children to the British National Crime Agency each year. Plans to switch on end-to-end encryption for all private messaging will reduce the number of cases that Facebook is able to uncover, Monika Bickert, the firm’s head of global policy management, told the committee on Wednesday. Asked by the committee’s chair, Yvette Cooper, to estimate the number of cases that would “disappear” under the switch, Bickert replied: “I don’t know the answer to that. I would expect the numbers to go down. If content is being shared and we don’t have access to that content, if it’s content we cannot see then it’s content we cannot report.” Cooper, who cited estimates from the US National Center for Missing and Exploited Children that 70% of reports from Facebook would be lost, expressed shock at the decision. “Why on earth – why, seriously, why is Facebook trying to introduce something that will put more children at risk, that will make it harder to rescue vulnerable children? Why are you doing this?” Bickert said: “We want to make sure that we are providing an experience that keeps people safe, especially for the crimes that are most at home, and most serious to them. In the UK, adults who were surveyed have said that the crimes online that are most concerning to them are data loss and hacking. “I spent my background as a prosecutor working on cases like violent offences to children and human trafficking offences, but I also want to be mindful of all the different types of abuse that we see online. I don’t think there’s a very clear answer on how to keep people the most safe most of the time. This is something also that governments have struggled for as long as I have studied or been aware of it.” On Tuesday the NSPCC called on Facebook to resume scanning for indications of child abuse in the EU. The social network has stopped one programme intended to protect children owing to fears that a new EU privacy directive rendered it unlawful, but the children’s charity argued that Facebook had drawn the wrong conclusion, and pointed to continued efforts from companies including Google and Microsoft to back up its assertion. Earlier in the committee hearing, Twitter admitted that its platform had played a part in the violence at the US Capitol on 6 January. “My colleagues were shocked watching the events in the Capitol and I think it’s impossible for anyone to look at that and not think ‘did we play a part in this?’” said Twitter’s head of policy, Nick Pickles. “And we have to conclude: yes. “Four years ago we’d have had a different answer. There’s not been an obvious tipping point. Last year we looked at QAnon, for example, and deamplified it; this year, we changed our approach and aggressively removed 70,000 accounts. Knowing what we now know, would we have removed them earlier? Yes.” Twitter’s admission of failings is in stark contrast to Facebook, whose chief operating officer, Sheryl Sandberg, last week denied the site had a major role in the riots. “I think these events were largely organised on platforms that don’t have our abilities to stop hate, don’t have our standards and don’t have our transparency,” Sandberg told a conference organised by Reuters. Her remarks were met with disbelief, as reporters continue to catalogue groups with tens of thousands of members on Facebook who were openly planning events with slogans such as “If they won’t hear us, they will fear us: Occupy Congress”.