Tory leadership contender Robert Jenrick says he regrets ordering children’s murals to be painted over at an asylum centre, following a backlash last year.

The former immigration minister instructed workers to cover up cartoons of Mickey and Minnie Mouse on the walls at an accommodation centre for unaccompanied child migrants in Kent.

The incident has come under renewed scrutiny since Jenrick joined the race to succeed Rishi Sunak as Tory leader, and he told LBC he would “probably” act differently “if I had my time again”.

Jenrick also stood by his claim that UK special forces were killing rather than capturing terrorists for fear of having to release them under human rights law.

When asked about why he made the decision to paint over murals, he said he was “very worried” about adults “coming into our country illegally and posing as children”.

He added: “So I did feel that it was important that at the initial point of arrival, we treat these places as law-enforcement environments with a view to trying to weed out those people who are actually just posing as children.

“I think that was the right decision, but of course there are lessons to be learned from it, and I probably would have done things differently if I had my time again.”

Pressed if this meant he would not do it again, he said: “No I wouldn’t, but what I did want to do then and I feel just as passionately about today, is that we have got to weed out those people who are posing as children when they first arrive.”

Jenrick, one of the final two in the Tory leadership contest alongside Kemi Badenoch, claimed he wanted to treat children in a compassionate way and that was shown by his work in closing down “rudimentary” hotels used to accommodate child migrants.

Seeking to build a broad support base, he says he’d be “delighted” if the two leadership candidates knocked out of the contest this week, Tom Tugendhat and James Cleverly, both seen as less right-wing, would join his shadow cabinet.

However, Jenrick also told BBC Radio 4’s Today programme shadow cabinet ministers would be required to support leaving the European Convention on Human Rights (ECHR) under him – a stance that has divided the Tory party during the leadership contest.

He claimed there was “consensus” in his party that the ECHR “is not working in the interests of the British people” and his time as immigration minister had hardened his views.

“I saw that we as a country were not able to do the most basic duty of the state which is to secure our borders,” he said.

“We weren’t able to remove dangerous criminals from the country, we weren’t able to remove terror suspects from the country.

“We certainly weren’t able to set up a robust but important and credible deterrent such as the Rwanda one because of our continued membership of the ECHR.”

Asked whether all shadow cabinet ministers would be required to support the idea, he said: “It would be one of the stable of Conservative policies. Yes – we would go into the next election with it in our manifesto.”

Jenrick has been criticised by both Tugendhat and Cleverly for his claims that human rights laws are hindering soldiers from capturing terrorists, which he uses to justify his pledge to leave the ECHR should he become party leader.

The claims were made in a video promoting his leadership campaign, Jenrick said: “Our special forces are killing rather than capturing terrorists because our lawyers tell us that if they’re caught the European Court will set them free.”

Former Attorney General and Conservative MP Dominic Grieve dismissed the claims as “twaddle”, adding leaving the ECHR “will do nothing” to improve the situation.

Tugendhat, a former soldier, called for Jenrick to take down a video where he made the claim, which he said was a “very serious accusation” showing “a fundamental lack of awareness of military operations, the command chain, and the nature of the law in the armed forces”.

But Jenrick said: “I continue to stand by the remarks that we made.

“The point that I was making then, which has been defended by a group of senior former special forces officers recently in a letter in The Times, was that it can’t be right that our military planners are having their discretion fettered as a result of the ECHR and our human rights apparatus.”