The Archbishop of Canterbury has brushed off criticism about possibly heading up a new Citizens' Forum on Brexit, saying the invitation to chair the proposed assembly is an "unexpected privilege". 

Justin Welby said he was prepared "in principle" to accept the invitation "subject to some conditions which have not yet been met". 

"It's an unexpected privilege to be asked to chair a proposed Citizens' Forum on Brexit. In the past this kind of gathering has, in many places and in difficult situations, opened the way for careful deliberation – if it's done at the right time and is genuinely representative," he said. 

He went on to outline his conditions for acceptance of the role, the first being that the forum not seek to stand in the way of Brexit. 

"The main three are first, and indispensably, that the Forum should not be a Trojan horse intended to delay or prevent Brexit in any particular form. That power can only be exercised by the Government and MPs in parliament. A Forum must be open to all possibilities," he said in a statement.

"Second, that it has cross party support (although its members will not be politicians). Third, the process must have time to be properly organised." 

Former Tory leader Iain Duncan Smith has been outspoken in his criticism of the Archbishop and the assembly, calling the proposals "deeply inappropriate".

He told The Times: "I generally don't criticise the archbishop but he shouldn't allow himself to be tempted into what is essentially a very political issue right now. This assembly is designed to destabilise Boris Johnson's position. As such I hope he will recognise the deeply political nature of this."

In his statement, the Archbishop defended taking up such a position, saying that it was "obviously right" that churches along with others should "contribute to the emergence of a dynamic and united country post-Brexit, however it may be achieved".

"Every one of us must play the part they can in this task," he said. 

"The need for national healing and eventually for a move towards reconciliation is essential, and will take much time, a deep commitment to the common good, and contributions from every source.

"This Forum is only one of many different efforts being made inside the political world and across the country before and after Brexit. Every effort counts.

"Let us pray for all those in government, parliament and political leadership. Let us pray for the people of this country whose lives will be affected in many ways by the momentous decisions that are made."