Official figures show 900 women were forced to disclose their child was conceived as a result of rape to claim social security help under the government’s two-child cap on benefits.

The government figures reveal in its first three years, 243,000 households containing 911,000 children were affected by the controversial policy, which was designed to deliver £1bn in welfare savings.

Opposition MPs condemned the two-child limit – which was launched by the former chancellor George Osborne in 2015 and came into force two years later – as a major driver of child poverty that should be scrapped.

The policy bars parents from claiming the child element in tax credits or universal credit for third or subsequent children born after 6 April 2017. Plans to extend the cut, worth £2,780 per child to those born before 2017, were dropped after an outcry.

Although the policy was introduced supposedly to force families on benefits to make the same financial choices as those in work, the government’s figures show that nearly three out of five households affected have at least one adult in work.

Families hit by the two-child limit lose £53 a week for every ineligible child compared with what they would have received before its introduction. A study published last year found affected families cut back on food, medication, heating and clothing.

The “rape clause” was introduced to enable women whose third or subsequent child was conceived through sexual assault to gain exemption from the limit. Other exemptions exist for multiple births and adoptions.

On its introduction, the rape clause triggered a furious reaction from women’s groups and rape crisis charities, which argue it is inhumane to oblige traumatised women to have to explain the circumstances of a rape as part of a benefits claim.

Scottish National party MP Alison Thewliss, who first identified the “rape clause”, famously called it “one of the most inhumane and barbaric policies ever to emanate from Whitehall”.

The government was forced by the courts in 2018 to introduce a separate exemption for kinship carers who were penalised by the two-child limit for having children of their own while already looking after younger siblings. The judge called the policy “perverse and unlawful”.

Responding to the latest figures, Thewliss said: “The UK government has no place to hide in the face of these damning statistics. Covid-19 has exposed the gaps in the social security safety net – I urge the new prime minister to do the right thing and scrap the two-child limit for everyone.

“Most shocking of all, 900 women have been forced to go through the process of claiming for an exception due to a non-consensual conception. Every single one of these women has been put in a position where they’ve had to fill in a form to prove their child was conceived as a result of rape or coercion, just to make ends meet.”

The shadow work and pensions secretary, Jonathan Reynolds, said: “These figures show just how many families the two-child limit is pushing into further hardship at a difficult time. No one could have been expected to foresee a crisis like Covid-19 when making decisions about the size of their family and it’s unfair to punish them for that now.

“The two-child limit is effectively an 18-year sanction on those decisions and is a major driver of child poverty. Labour would scrap it entirely as part of building a new social security system which provides a decent standard of living for all.”

A spokesperson for the Department of Work and Pensions said: “It’s unsustainable for benefits to automatically increase with family size. In 2019, 85% of all households had two or fewer children, therefore, it’s proportionate to provide support for a maximum of two children, and there are appropriate exceptions in place.

“We are committed to supporting the most vulnerable in society and understand the challenges many families are facing. That is why since the start of the pandemic we have injected £6.5bn into the welfare system, including increasing universal credit and working tax credit by up to £1,040 a year.”