An attack on Sadiq Khan by a Christian charity has provoked anger from a number of bishops and prominent church leaders.

In a letter to the Church Times Mark Russell, the chief executive of the Church Army, five bishops and several others wrote to express "anger at both the content and tone" of an article published by the charity Christian Concern.

The article entitled Londonistan with Khan? drew links between the new mayor of London and Islamic extremism and warned he would fuel an "increase in Islamic segregation in London leading to increased radicalisation". The article also suggests Khan will not support police in upholding the law in areas with high Muslim populations.

Russell, alongside the bishops of Southwark, Chelmsford, Woolwich, Willesden and Beverley, branded the article "ill-informed, dangerous and wrong".

They wrote: "We believe this is deeply damaging to the cause of the gospel in London."

Speaking to Christian Today, Russell, who is a member of the Church of England's general synod, said the article was "misjudged and unwise".

He said he wanted to ensure no one thought Christian Concern spoke for the Church of England and called on the charity to apologise to Khan.

He added many other bishops and church leaders had wanted to sign it but had been unable to meet the deadline for the weekly newspaper.

The letter praised Khan's integrity and said he was "committed to inclusion". It praised Khan's decision to move his signing-in ceremony from London's City Hall to Southwark Cathedral and said it showed he would work for the whole city.

"We wish him well as mayor," they wrote. As well as the five bishops, other signatories included the dean of Southwark, Andrew Nunn, the prolocutor of the convocation of Canterbury, Simon Butler and seven others.

Andrea Minichello Williams, chief executive of Christian Concern, said the authors of the letter did not engage with the main substance of the article but used the letter "as a platform to promote their own political message". She said Christian Concern expressed the views of many Christians and accused the authors of trying to squeeze them out of public life. 

She told Christian Today: "At Christian Concern we are committed to praying for Sadiq Khan whilst continuing to speak of Jesus Christ in public life."

The letter comes after a heated campaign where Khan was repeatedly accused of having links with extremism by his Conservative rival Zac Goldsmith. Despite this Khan won convincingly with the highest personal mandate of any politician in UK history.