Boris Johnson has called for a referendum on Britain’s membership of the European convention on human rights, a move likely to increase pressure on those vying for the Conservative leadership to follow suit. The former prime minister told the Daily Telegraph there was a “strong case” for a vote on the ECHR, which some Tories blame for hampering their efforts to deport asylum seekers to Rwanda. Johnson, who is promoting his memoir, remains popular with many Conservative members, who will soon vote for the next party leader. Robert Jenrick, a frontrunner, is the only candidate to promise to take Britain out of the ECHR. Johnson, asked if he would support a referendum on the ECHR, told the newspaper: “I would. I think it has changed. It has become much more legally adventurist. It’s trying to second guess what national jurisdiction should do.” He added: “There’s a strong case for a proper referendum, a proper discussion about it because I’m not certain that it actually provides people with protections that they wouldn’t otherwise have.” Britain’s membership of the convention has become one of the most hotly contested issues in the Tory leadership battle. Some Conservatives have blamed the court in Strasbourg, which interprets the convention, for the previous government’s failure to implement the Rwanda deportation scheme, even though it was blocked by the UK supreme court. While Jenrick, the former immigration minister, argues the UK cannot have an effective migration policy while a member, his rivals have accused him of offering an overly simplistic solution to a complex problem. Speaking at this week’s Conservative party conference in Birmingham, Tom Tugendhat, one of the other three candidates, argued: “This is about visas, not about foreign courts.” Johnson also told the Telegraph that while he was foreign secretary, a listening device was found in his private bathroom after it had been used by Benjamin Netanyahu, the Israeli prime minister. He added the timing “may or may not be a coincidence”. The former prime minister is also under pressure to explain his role in the deal ceding control of the Chagos Islands to Mauritius. The agreement was announced on Thursday by the prime minister, Keir Starmer, but Labour sources have pointed out that negotiations began under the previous Conservative government. Sources close to James Cleverly, the former foreign secretary and Tory leadership candidate, on Thursday reportedly blamed the former prime minister Liz Truss for starting the talks. But a spokesperson for Truss sought to highlight Johnson’s role. “It was Boris Johnson who asked Liz to talk to [the Mauritian] prime minister Jugnaut about this at Cop26, which she did,” the spokesperson said. “But she was absolutely clear that we would and should never cede the territory.” Johnson will be interviewed on Friday night by ITV’s Tom Bradby, after a similar interview on the BBC was cancelled after the interviewer, Laura Kuenssberg, mistakenly emailed Johnson her briefing notes.