Sir John Major has criticised the former Conservative government’s Rwanda scheme, saying it was unsuitable for the 21st century and was “un-Conservative and un-British”.

The Tory former prime minister expressed frustration about “the way society has come to regard immigration as an ill” and said he did not think the policy would have acted as a deterrent.

In one of his first acts as prime minister, Keir Starmer in July scrapped the controversial policy, which the Tories believed would deter asylum seekers by sending those who arrived in the UK illegally to the east African country.

Major said: “Are they seriously saying to me that somewhere in the back woods of some north Africa country, they actually know what the British parliament has legislated for? I think not.

He added that people who came to the UK on small boats did so “because they’re not quite sure where to go”.

On Monday Labour announced the money that had been allocated to pay for the previous government’s Rwanda scheme would go to the Border Security Command.

Major said of the Rwanda scheme: “I thought it was un-Conservative, un-British, if one dare say in a secular society, unchristian, and unconscionable and I thought that this is really not the way to treat people.”

In an interview with the BBC’s Amol Rajan, he added: “We used to transport people, nearly 300 years ago, from our country. Felons, who at least have had a trial, and been found guilty of something, albeit that the trial might have been cursory.

“I don’t think transportation, for that is what it is, is a policy suitable for the 21st century.”

Major, who served as prime minister from November 1990 to May 1997, said he had not decided which Tory leadership contender to support. Robert Jenrick, Kemi Badenoch, James Cleverly and Tom Tugendhat are the remaining candidates in the contest.

He said he hoped the Tories would bring people back to the party who are “genuinely centre right”, and said a Tory merger with Reform UK would be “fatal”.

Reflecting on the Tory leadership hopefuls, he said: “I would like to support someone who’s going to look at the long-term problems and make a suggestion as to which direction we should go and bring people back into the party who are genuinely centre right.”

He added: “The only party that can legitimately appeal to the centre right is the Conservative party. And that is what we have to do, we have to decide where our natural support really lies and appeal to them.

“People may have made a misjudgment about the last election. We lost five votes [seats] to Reform UK and people are jumping up and down, and some, rather reckless people are saying, well we must merge with them.

“Well, that will be fatal.”

Asked whether Nigel Farage should join the Conservative party, Major said he did not “share that view”. He added: “I don’t think he’s a Conservative, and he’s spent most of his time in the last few years telling people how much he dislikes the Conservative party and would like to destroy it. I don’t think that’s a terribly good background for bringing someone into the party.”