The Bishop of Bradford is among 43 Bishops, including the Archbishop of Canterbury, who have written an open letter condemning Government plans to change the benefits system, saying it will have a “deeply disproportionate” effect on children.

The letter has warned that 200,000 children will be pushed into poverty if plans to change the system go ahead in their current form.

Iain Duncan Smith, the Work and Pensions Secretary, who is attempting to steer the reforms through Parliament, said the Welfare Benefits Up-rating Bill, which will cap benefit rises at one per cent a year until 2016, is needed to help get spending “back under control” and create a fairer deal for taxpayers.

But in the letter the Bishops have called on the House of Lords to take for action to “protect children from the impact of this Bill” when the proposed legislation is debated this week.

The Archbishop of Canterbury, the Most Reverend Justin Welby, who will be enthroned at Canterbury Cathedral on March 21, said: “As a civilised society, we have a duty to support those among us who are vulnerable and in need.

“When times are hard, that duty should be felt more than ever, not disappear or diminish.”

The Bishop of Bradford, the Right Reverend Nick Baines wrote about the issue on a blog post today. He said: “This letter is not anti-government or anti-Cameron; it is pro-children.

“The question of priorities remains unanswered: we can bail out banks to the tune of billions of pounds, but it’s the poor who have to pay? The Government’s language has become increasingly and deliberately disingenuous, lumping people on welfare benefits into the category of ‘feckless scroungers’ who lie in bed watching other people go to work. Yet, they know that most people being hit by welfare cuts and the bedroom tax are low-paid working people.”

Mr Duncan Smith tonight hit back at the claims. He told ITV: “This is about fairness. People who are paying taxes, working very hard, have hardly seen any increases in their salary and yet, under the last government, the welfare bill rose by some 60% to £200 billion. That means they have to pay for that under their taxes, which is simply not fair.

“That same system trapped huge numbers, millions, in dependency, dependent on the state, unable, unwilling to work. What is either moral or fair about that? That’s my challenge over to the bishop.”

Shadow Home Secretary Yvette Cooper said Labour would go ahead with a benefits increase linked to inflation this year. She said new mothers would lose £180 a year as a result of the one per cent cap.