An imam who questioned the Tory leadership candidates during a televised debate would not have been selected if the BBC had been aware he had made critical comments about Israel, the corporation has said.

Abdullah Patel asked the contenders about Islamophobia, but has been criticised for past tweets in which he wrote: “Every Political figure on the Zionist’s payroll is scaring the world about Corbyn. They don’t like him. He seems best suited to tackle them!”

He also shared an image endorsing the relocation of Israel to the US as a way of solving the Israel/Palestine conflict.

Rob Burley, who edited the programme, said Mr Patel’s Twitter account had been deactivated ahead of his appearance on the BBC debate – meaning his tweets could not be read.

He said: “It was AFTER the show that Mr Patel reactivated his account revealing his tweets.

“We wouldn’t have put him on the programme if these were public before broadcast, but they were not. We also carried out a number of other routine checks which didn’t uncover anything untoward.”

Mr Patel has taken down his Twitter account again after the past tweets came to light.

Earlier, BBC Radio 5 Live presenter Nicky Campbell, who had Mr Patel on his breakfast show, apologised and said the imam had made “extremely disturbing” remarks on Twitter and that he was “sorry” the broadcaster had not checked beforehand.

Campbell tweeted: “I would like to apologise. We had the Imam from the BBC Tory leadership debate on our programme this morning.

“His social media comments have been extremely disturbing. We should have checked. We didn’t. I’m sorry.”

In the debate, Mr Patel asked the five candidates whether they believed words had consequences, and said he had seen first hand the impact of Islamophobic rhetoric on his community.

Boris Johnson said he was “sorry for the offence” his comments about veiled Muslim women looking like “letter boxes” and “bank robbers” had caused, while Michael Gove condemned Islamophobia as “repugnant” and attacked Labour leader Jeremy Corbyn for comments he claimed were “disgusting” and anti-Semitic.

Home Secretary Sajid Javid urged all the candidates to commit to an external investigation into the issue within the Tory Party, and his rivals nodded in agreement.

Writing on Twitter after the debate, Mr Patel said he had asked the question because he wanted the candidates to promise that “things would change”, adding: “The hate is real.”

“As an Imam, I’m exposed to many incidents which happen in my community, and of course, as a visible Muslim, I also witness it first hand. I have received numerous incident reports of blatant racism against members of my community, from spitting and swearing at Muslim women … to asking students coming to my mosque if they had bombs in their bags,” he wrote.

He added: “What I got as a response was nothing short of disappointing and deluded: @BorisJohnson forgot my name, spoke about his G(reat) grandfather and about Iran. Gove used the opportunity to have a dig at @jeremycorbyn.

“@Jeremy-Hunt used the chance to speak about how he can’t be racist because he has an immigrant wife, and @RoryStewartUK forgot that this is also OUR country. The only positive from the debate was @sajidjavid making them all commit to an independent investigation into Islamophobia in the @Conservatives.”

In his response to the question, Mr Johnson said he believed his Muslim great-grandfather would have been “very proud” to have seen him become foreign secretary.

He added that, when his great-grandfather came to the UK in 1912, “he did so because he knew it was a beacon of generosity and openness and a willingness to welcome people from around the world”, adding: “If I am prime minister, I will ensure that that is the way our country acts and behaves.”

At one point he appeared to forget Mr Patel’s name, referring to him as “my friend over there”, before presenter Emily Maitlis interjected: “Abdullah”.