Facebook, Google and Twitter have been criticised by a UK parliamentary committee for their refusal to report users to the police when they remove criminal posts.

Representatives of all three companies appeared in front of the home affairs select committee to discuss their progress on tackling hate speech and terrorism on their platforms. But MPs said they were shocked to learn that none of the companies had policies of reporting criminal material to law enforcement, except in rare cases when there was an immediate threat to life or limb.

Yvette Cooper, the chair of the committee, pressed Facebook’s public policy director, Neil Potts, on whether or not the company was reporting to New Zealand authorities the identities of people the company believed were actively and deliberately attempting to evade its filters and upload footage of the Christchurch shooting.

“We’ve been told by the counter-terror chief commander, Neil Basu, here that very often the social media companies do not report to the police incidents which clearly involved breaking the law,” Cooper said.

“That although you might remove content, you don’t refer it to the police. That’s why I think this is a significant question, about whether or not you have referred information to the police about individuals who were deliberately uploading in order to spread terrorist propaganda.”

Potts said the decisions were made on a “case by case” basis, but that “we do not report all crimes to the police”.

“There are obviously different scales of crime,” Potts said, before being interrupted by Cooper, who told him that “a crime is a crime … I’m trying to understand whether Facebook reports crimes, on your platform, to the police. And who are you to decide what’s a crime that should be reported, and what’s a crime that shouldn’t be reported?”

Potts said: “These are tough decisions to make on our own, and these are places where government can give us more guidance and scrutiny.”

Representatives of both Twitter and Google admitted neither of their companies would necessarily report to the police instances of criminal material they had taken down. Twitter’s Katy Minshall said that, like Facebook, the company “will reach out to law enforcement when there is a threat to life”, while Google’s Marco Pancini said: “We have policies that are in line to the ones of our colleagues.”

A visibly frustrated Cooper responded to Pancini, saying: “The issue is whether or not you are letting law enforcement know about the crimes that are being committed on your platforms. It is a very real concern, because you are effectively making these crimes possible.

“You are facilitating these crimes, and I accept you are doing much more than you were 18 months ago to respond to them and take that material down. But you are not actually reporting the crimes that your platforms are making possible. Surely that is a serious problem for people, right across the world, who want to make sure that crimes are not being committed?”

Pancini faced further criticism from the committee for his inability to explain what YouTube was doing to tackle potential radicalisation via the platform’s algorithmic recommendations. The SNP MP Stewart McDonald revealed that when a member of the committee staff, on a new YouTube account, “searched for ‘British news’, ‘British politics’, ‘football’, ‘music’, ‘TV’, and ‘games’, they were recommended videos by a rightwing commentator, a very controversial psychologist with essentially what I regard as racist views, and a far-right figure in the UK.”

Pancini said YouTube was working to promote “authoritative” videos on searches for breaking news and “speech”. He said it was working on more general solutions to algorithmic radicalisation, prompting further dismay from Cooper.

“You are maybe being gamed by extremists, you are effectively providing a platform for extremists, you are enabling extremism on your platforms,” she said.

“Yet you are continuing to provide platforms for this extremism, you are continuing to show that you are not keeping up with it, and frankly, in the case of YouTube, you are continuing to promote it. To promote radicalisation that has huge damaging consequences to families’ lives and to communities right across the country.

“Particularly to YouTube, I am appalled that the answers you have given us are no better than the answers your predecessors have given us in every previous evidence sessions. As far as it seems that your organisation in particular is concerned, very little has changed.”