Welby posted a gushing message after the event, saying it was a "pleasure to welcome friends", adding that he had enjoyed "the honest sharing of different perspectives".

Lord Carlile KC, the independent reviewer of terrorism legislation, said the Church had to be more careful in choosing its partners for interfaith events, citing the report published earlier this year by Sir William Shawcross on the government's Prevent programme that is supposed to curb extremism.

He added it was a "serious error of judgment" to engage in discussions with those who have been seen as "apologists" for "extremism".

Stephen Crabb MP, the Commons Parliamentary Chairman of Conservative Friends of Israel, said: "These reports represent another painful reminder of the Iranian regime's increasingly emboldened interference in the UK. It is particularly troubling that invaluable interfaith work is being undermined by extremists."

The day-long gathering at Lambeth Palace library was organised by the Christian Muslim Forum (CMF), a taxpayer-funded group of which Welby has been patron since it was founded in 2006. Welby has welcomed Shomali to Lambeth Palace on at least two previous occasions, in 2016 and 2017.

For years, Shomali has served as co-director of an institute in the Iranian city of Qom that was led until 2021 by a hardliner who advocated suicide bombings against Israel and believed "Zionists" were the "fundamental source of evil".

Kozbar, who is also the general secretary of Finsbury Park Mosque, met Hamas leaders on a visit to Gaza in 2015 and paid tribute to the terror group's founder, Ahmed Yassin, following a visit to his grave.

There is no suggestion that Welby endorses extremist views, and a spokesman for Lambeth Palace told the JC that not "everyone is in full agreement on important issues" at such gatherings.

He added that the meetings were "a chance to explore and work through differences and build trusted relationships". Two weeks ago, Welby rejected the claim that Israel was an apartheid state.

But the meeting raises serious questions about the selection of partners for interfaith events and the influence it may give them. CMF's latest annual report, covering the calendar year 2021, says it has "built links" with both the ICE and the MCB, which has been blacklisted by successive Labour and Conservative governments since 2009 because of its alleged support for violence against Israel.

In 2019, the CMF held a "twinning event" between the ICE and a church near the mosque, St Augustine's in Kilburn Park.

For ten years until the end of 2021, the CMF was partly funded by taxpayers, receiving grants totalling £341,000 from the forerunner of what is now the Department for Levelling Up, Housing and Communities, led by Michael Gove.

Both as head of the ICE and after stepping down, Shomali has travelled widely and repeatedly taken part in interfaith events with both Protestant and Catholic clergy. He was pictured sitting next to Welby at Lambeth Palace in December 2015, when he posted on Facebook that the Archbishop had welcomed "Shia theologians to Lambeth Palace at the end of three days of dialogue with Christian theologians at the University of Oxford".

However, in the same period he has maintained his proximity to the Iranian regime. In 2014, Shomali held a "celebration" at the ICE to mark the 35th anniversary of Iran's Islamic Revolution. Among its guest speakers was the former Labour leader Jeremy Corbyn.

Shomali also held events venerating Ayatollah Ruhollah Khomeini, Iran's revolutionary leader, whose accession to power was followed by the persecution of Iran's 1.4 million Christians.

And in an essay published in 2017, Shomali likened gay marriage to bestiality, writing: "A hundred years ago, it would have been unthinkable for gay marriages to be sanctioned... Perhaps a day will come where some will desire marriage with animals."

In 2016, Shomali published a personal "letter of appreciation" from Khomeini's successor, Khamenei, extending "thanks to your excellency for your unreserved efforts".

Khamenei has repeatedly called for the destruction of Israel, describing it in speeches as a "cancerous tumour" that must be excised. In addition to his other posts, for many years Shomali has been a director of the Imam Khomeini Education and Research Institute in Qom, the holy city that is the ideological epicentre of the Iranian regime.

It was founded in 1991 by Ayatollah Mohammad-Taqi Mesbah-Yazdi, who Iran experts say was one of the most extreme of all Iran's revolutionary leaders and campaigned against the liberalisation of Iranian society, even encouraging acid attacks against Iranian women for "improper hijab".

Mesbah-Yazdi remained head of the institute until his death in 2021. Kasra Aarabi, the director of the US-based campaign and research organisation United Against Nuclear Iran, said: "Mesbah-Yazdi was the principle architect of the doctrine propagated by Khamenei and the Islamic Revolutionary Guards Corps, which says Israel and global Jewy must be annihilated in order to permit the return of Imam Mahdi, the 9th-century figure messianic figure whom Shia Muslims believe will reappear one day to wage an apocalyptic war against non-Muslims. He was one of the regime's most violent, Islamist extremist clerics."

An interview with Mesbah-Yazdi published in the online magazine Salon in 2009 stated: "His fixed mocking smile cannot conceal his cold nature.

He openly advocates suicide bombings, calls for the carrying out of the fatwa imposed against author Salman Rushdie and demands 'the blood of any person who insults Islam'. And he considers 'the Zionists' to be the fundamental source of evil on Earth."

Like Shomali, Mohammed Kozbar, the general secretary of Finsbury Park Mosque and the MCB's deputy secretary general, is a regular at interfaith events, and has even preached in a church near the mosque, St Mary's in Stoke Newington.

He met leaders of the Hamas terror group on a visit to Gaza in 2015 and described its founder Ahmed Yassin as "the master of the martyrs of resistance".

In response to previous JC reports, Kozbar has insisted he is committed to working with Jews against both Islamophobia and antisemitism, but he was filmed in 2011 saying he looked forward to "the end of Israel, Insh'Allah".

Last year, he also hosted antisemitic Egyptian imam Omar Abdelkafi at his mosque, describing him as a "beloved" preacher.

Abdelkafi is on record quoting from the Protocols of the Elders of Zion, the notorious antisemitic forgery, and his Facebook posts include a prayer to "liberate the al-Aqsa mosque in Jerusalem of the filth of the Jews".

Less controversial -- but also at the event -- was Omar Salha, the founder of interfaith group the Ramadan Tent Project, which Welby has supported.

The JC revealed two years ago that Labour leader Sir Keir Starmer had pulled out of a meeting with Salha's organisation after learning he had shared a tweet calling for the boycott of Israeli goods and expressed support for Cage, whose research director described the Isis executioner Jihadi John as a "beautiful young man".

Salha tweeted in 2017: "Time for those who stand for the values of justice and liberty to support UK Cage and not be intimidated by the powers that be."

At the start of Ramadan in March, Welby posted a message saying: "Special thanks to Muslim communities who've pioneered community iftars such as the Ramadan Tent Project".

A Lambeth Palace spokeswoman said: "Every year the Christian-Muslim Forum has a gathering to bring together its members and to mark the positive work carried out by CMF. This is what happened last Thursday.

The CMF was set up to bring together Muslims and Christians from a wide variety of denominations and traditions. The purpose is to work together for the common good.

"The Christian Muslim Forum organised the event last week, and Lambeth Palace Library hosted it. When groups like this meet at events like Thursday's it does not suggest that everyone is in full agreement on important issues, but it is a chance to explore and work through differences and build trusted relationships.

The Archbishop of Canterbury has a clear stance against antisemitism, and any form of discrimination and prejudice. He is committed to non-violence and peacebuilding, and events like last Thursday's are a chance to respond -- in solidarity -- to challenges affecting all our communities."

The CMF, Shomali, Salha and Kozbar have been asked for comment.