A group that sends aid to Christians living in Muslim territories is seeking to prepare churches in Britain in case of a terrorist attack amid the rising terror threat posed by the Islamic State.

Critics immediately pounced on the move, with one academic calling it "nonsensical and ridiculous," noting that UK churches are not even at the top of the ISIS' target list, making the effort being undertaken by British charity Barnabas Fund an over-reaction to ISIS' terror campaign.

Barnabas Fund, which offers "hope and aid for the persecuted church," earlier invited over 50 church leaders to attend a half-day session at Westminster's Central Hall on Tuesday to brief them on ways to protect their congregations and buildings against militants, the Guardian reported.

The conference was headed by the group's international director, Patrick Sookdheo, who was previously an adviser on Islam to the Ministry of Defence.

Representatives from the police were also invited to give advice.

An email from the Fund with the subject "Protecting British churches from terrorist attack" was earlier leaked to the media. It warned: "Given the dramatic growth of ISIS in the Middle East and the increased anti-Christian rhetoric and attacks from that group, plus the recently thwarted attempts to attack churches in Paris, the possibility of an ISIS attack on British churches cannot be discounted."

"The meeting will consider critical vulnerabilities and how these can best be mitigated. It will include practical advice for realistic measures that local church leadership can adopt to protect their congregations and buildings without causing undue alarm or hindering a congregation's ministry and outreach," read the email.

Sookdheo noted the "growing anti-Christian persecution, where terrorist organisations are increasingly focusing on Christian communities."

"Extremists are trying to stir up inter-religious strife, sectarian conflict," he said. "Churches are vulnerable places because they are open places."

Churches were advised to work closely with authorities, following the arrest of a Muslim man in France back in April for allegedly plotting attacks on churches. In Charleston, South Carolina, nine black parishioners were murdered in a historic church, showing how vulnerable churches are to attacks, Sookdheo noted.

"The advice we give is to work closely with the police in the area and also with the local imam. What we want is to build community cohesion," he said.

However, some analysts said the conference "could send the wrong message" and worsen tensions between Christians and Muslims.

"But this is what ISIS has been working towards—making people scared and feeling they are targets," said Charlie Winter of the Quilliam Foundation, a counter-extremism thinktank.

"I haven't seen or heard anything to suggest that churches in the UK are being targeted by I SIS," he added.

One academic said UK churches are not even at the top of the ISIS' target list, making the conference an over-reaction to ISIS' terror campaign, wrote the Church Times.

"The idea is bunk. It is nonsensical and ridiculous," said Fawaz Gerges, professor of International Relations at the London School of Economics. "The idea does not make sense to me. It is not a priority for ISIS or al-Qaeda."

Anthony Glees, director of the University of Buckingham's Centre for Security and Intelligence Studies, voiced a similar opinion: "I know of no intelligence that [ISIS militants] are planning to [attack churches]. It is possible to believe that there may be an intention on the part of ISIS supporters to attack Christian churches but to the best of my knowledge there is no evidence that they have the capability to do so. In that sense I would say that this is almost certainly an over-reaction to the situation."

Gerges was worried that the conference would instead provide the ISIS a "moral boost" because churches will be portrayed as being scared of the extremist group.

"It tells them 'We are terrorising our enemies,'" said Gerges.

"You're playing into the hands of the radicals who say 'We are a fifth column in your society.' It's not true at all."

The Barnabas Fund's conference was planned as "a confidential, closed-door meeting, not to be made public. Now it has become a public issue. It's not us here creating the problem," said Sookdheo.