Anas Sarwar has backed Keir Starmer over Labour’s benefit cap u-turn, despite anger from MSPs and charities. 

The Glasgow MSP insisted he was still against the rape clause but warned that immediately scrapping the two-child limit could “spook the markets” leading to a repeat of the catastrophe surrounding Liz Truss’s mini-budget.

He told the Scotsman: "We are not going to be able to fix everything straight away and we’re not going to be able to do everything that we want to do or need to do because of the state of that financial crisis.

"I think having that grown-up approach most people will recognise and appreciate.”

READ MORE: Sarwar backs Starmer over two child benefit cap u-turn

In an interview with the BBC’s Laura Kuenssberg on Sunday, Sir Keir refused to be drawn on a number of other spending commitments but was unequivocal on the limit.

“We're not changing that,” he said.

That was despite scrapping the policy being a key vow in the party's 2019 general election manifesto and in his 2020 leadership bid. 

The two-child policy was introduced by George Osborne in his 2015 budget. It came into effect two years later, with households claiming child tax credit or universal credit unable to claim for a third or subsequent child born after 6 April 2017.

Last week, the latest statistics revealed that 1.5 million children were growing up in families impacted by the cap.

According to the Resolution Foundation analysis, the poorest working-age households are currently £780 a year poorer because of the limit, but as the policy applies to more and more children and becomes fully rolled-out by 2035, they will be £1,310 worse off.

Children's charities, including Barnados and the Child Poverty Action Group, have said this "tax on siblings" is the "biggest driver of rising child poverty in the UK today."

There is an exemption for families where a child is the result of “non-consensual conception.”

The only way this can be obtained is for the child's mother to disclose their rape to the Department for Work and Pensions.

There were 2,590 households affected by this so-called "rape clause" last year.

READ MORE: Analysis: Labour in turmoil as Starmer refuses to scrap the rape clause

In his interview with the Scotsman, Mr Sarwar said he would “continue to urge” colleagues in the UK party to “move as fast as they can to address the issue of the two child cap.”

However, he added he was “cognisant of the fact that they have to do it within the fiscal rules that are set because we cannot have a repeat of the Kwasi Kwarteng/Liz Truss budget that means if we get it wrong, and we spook the markets, it means higher interest rates, higher inflation and higher mortgage payments for people across the country."

Mr Sarwar said: “I continue to believe that it is a heinous policy that is doing damage to families across the country and that it is exacerbating poverty. I know that my colleagues in the UK party continue to believe that as well.

"But what they are being up front and straight about is we have to look at the financial circumstances that we’ll find ourselves in.”

Reports suggest it could cost more than £1.5bn to ditch the limit. 

READ MORE: Anas Sarwar under pressure over Keir Starmer 'rape clause' u-turn

Meanwhile, Sir Keir could even face a rebellion from members of his Westminster frontbench.

A Labour source told HuffPo the Shadow Cabinet was “in meltdown over this.” 

They added: “There’s a lot of anger among MPs and some frontbenchers have threatened to resign.”

But one shadow cabinet member said: “It’s possible to both be critical of the two-child policy but also say we can’t make spending commitments. We have to be fiscally disciplined.”

A source close to Sir Keir told HuffPost UK: “You can think it’s a heinous policy but also accept that there is absolutely no money and unless there is £2 billion sloshing around, we can’t reverse it

“Members of the shadow cabinet who are unhappy should be setting out from their budget how we’re going to fund it.”