SCOTLAND’S children’s commissioner has attacked the UK Government over “callous” benefit cuts and the introduction of the so-called ‘rape clause’.

Tam Baillie said the changes to the system were being made even though ministers in Westminster were fully aware of the impact they will have in plunging more families and children into poverty.

He also backed charities for refusing to cooperate with a new policy that requires some women to prove they have been raped in order to receive child tax credits.

The changes to the benefit system, which were introduced last week, include child tax credit being limited to the first two children born in a family. It will apply to children born from this April and to completely new tax credit claims from next autumn.

The Child Poverty Action Group has estimated this will push another 200,000 children in the UK below the poverty line and working families with three children will miss out on up to £2,780 a year.

Baillie, who has published a blog on the issue, told the Sunday Herald the cuts were “policies of choice”.

He said: “It is not that the government isn’t aware this will put more families or more children into poverty. For me it is quite a callous calculation they are making.

“These are conscious policy decisions which the [UK] Government present as having to make certain difficult choices – but the way they fall is always on children.

“It is misplaced, as we know many of our social policy responses are trying to mitigate the impact of poverty in the early years of children’s lives. It is short-sighted as well.”

He added: “The shame of all of this is we are a rich society and we shouldn’t tolerate the levels of child poverty that we appear to tolerate.”

One exception to the two child limit on tax credits is if a woman can prove a third or subsequent child was born as a result of rape, by filling a form which has to be verified by a professional who is aware of the circumstances.

The policy has provoked an outcry, with First minister Nicola Sturgeon speaking out against it at the Women in the World summit in New York last week.

She told the audience: "It is a disgusting and disgraceful policy but that policy has been introduced by a woman Prime Minister.”

Leading charities including Scottish Women’s Aid and Rape Crisis Scotland have also said they will not “collude” with the policy, which forces women to disclose rape in order to receive child tax credits.

Baillie, who will step down from his post next month after finishing a six-year term as Children and Youn People's Commissioner, said he supported the refusal of women’s aid and rape crisis groups to not take part in the process.

Writing in the blog he added: “Given the low conviction in rape cases, how are these women supposed to prove this?

“We should be angry, very angry, that, yet again, measures taken by the UK Government hit the poorest, most vulnerable in our society— our families and children.”

The UK Government said the average number of children per family was 1.7 in 2012 and it is “fair and proportionate” to limit tax credit support to two children.

A spokeswoman added: “Our welfare reforms are incentivising work and restoring fairness to the system for those who need it as well as the taxpayers who fund it.

“This policy helps ensure parents on benefits have to make the same choices as those supporting themselves solely through work.

"Current claimants won’t see any reduction in their benefits as a result of this policy, and we will continue to pay Child Benefit for all children in a household.”

On the issue of the ‘rape clause’, the spokeswoman said it was crucial to “protect women who are faced with very difficult circumstances”.

She added: “We have always been clear this will be delivered in the most effective, compassionate way, with the right exceptions and safeguards in place.”