Police recruitment needs to be “far more rigorous”, a watchdog told MPs as he warned it would be “plainly inadequate” for forces to hire officers through a purely online process.

Chief inspector of constabulary Sir Tom Winsor told the Commons Home Affairs Committee that when police discover concerning attitudes and behaviour among trainee officers and during the recruitment process they should “root them out and throw them out” otherwise they are “storing up what could be a 30-year problem”.

Asked by MPs for his thoughts on the state of policing before he leaves his role at the end of March, Sir Tom also described the criminal justice system as “on its knees” and said a royal commission was “necessary.”

Discussing the implications of a recent report by the Independent Office for Police Conduct (IOPC) – which exposed violently racist, misogynist and homophobic messages exchanged by officers based at Charing Cross police station in London – he said forces must use techniques during the recruitment process to “recognise characteristics and behaviours which are inconsistent with the office of constable.”

He told the committee on Wednesday: “Clearly the communications in question were just disgraceful and appalling…

“The recruitment of officers needs to be far more rigorous… so that when these attitudes are revealed, when they are apparent, then the police should stop these people going any further in the police and get them out.”

Sir Tom said it is “incumbent” upon the police when they are assessing candidates to have “good techniques to recognise characteristics and behaviours which are inconsistent with the office of constable”, for example, a “fondness for violence, a fondness for the exercise of power over their fellow citizens, homophobia, misogyny, racial attitudes”.

“When those things are recognised the police should root them out and throw them out… they should not allow them to stay in the police or get into the police,” he added.

He said taking the attitude that someone will make a good officer and “we’ll knock these rough edges off” was a “disastrous policy”, adding: “It costs a lot of money to train a police officer and forces will be reluctant to abandon that investment by throwing out somebody like that but they must because otherwise they’re storing up what could be a 30-year problem.”

When asked whether online recruitment methods being used by some police forces were sufficient, Sir Tom said: “Where it takes place (it) is plainly inadequate.

“Online only is not enough. You need to get somebody in a room, you need to listen to them, you need to listen to them when their guard is down, when they’re not pretending.”

The recruitment process should look at how candidates behave with colleagues, supervisors and those carrying out the assessments and consider how someone acts in formal and informal surroundings to “draw out those attitudes and behaviour”, he said, adding: “When they see them, they need to take them very seriously.”

In light of the Charing Cross report, Sir Tom said he was confident concerns raised about similar behaviour would now be taken “very seriously indeed”, although he said “clearly there were significant failures in the past”.

He also agreed there should be a royal commission on policing, but added: “Unfortunately, government ministers don’t really much like royal commissions unless their objective is to kick things into the long grass.

“The government did promise in its 2019 manifesto a royal commission on criminal justice.

“Now the pandemic has intervened, but I have no real expectation we’re going to see that this side of whenever the next election is.

“I think that’s regrettable. I think a royal commission on criminal justice is necessary.

“And it has the advantage that it could, as long as its terms of reference are not drawn too narrowly, be able to cover the police but also the other three elements of the criminal justice system – prosecutions, prisons and probation.”