Scottish Labour’s candidate for a key Westminster by-election has been urged to “come clean” over whether Sir Keir Starmer’s party would keep the Conservative benefit cap in place.

The appeal for Labour’s Michael Shanks to state his position ahead of the Rutherglen and Hamilton West seat comes after new analysis showed that keeping the policy in place could have a damaging impact on hundreds of families in the constituency.

The analysis by the SNP, using UK Government Department for Work and Pensions (DWP) data, shows around 1,300 families in South Lanarkshire, have seen their incomes slashed as a result of the Tory benefit cap, which reduces the total amount of financial support families can get.

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The challenge comes days after the Labour Party was forced to admit it would keep the Tory bedroom tax and two-child cap, which has pushed more than 20,000 Scottish children into poverty.

Labour used to oppose the two-child cap, but Sir Keir has suggested he would keep the controversial policy in place if he becomes the next prime minister.

Anti-poverty charities and some within Scottish Labour have criticised Sir Keir’s support of the policy.

According to analysis, overall, the benefit cap has left the poorest families in Scotland more than £70 million worse off since 2013.

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A total of 28,188 households in Scotland have seen their housing benefit or Universal Credit payments reduced as a result of the benefit cap, including 24,546 households with children.

The analysis shows that on average impacted families in Scotland lose £50 a month as a result of the benefit cap.

The analysis shows that the rate of the benefit cap has fallen significantly behind inflation, meaning Scottish households subject to the cap are now significantly worse off in real terms than they were when the policy was first introduced.

The annual UK Government benefit cap for Scotland is currently £14,753 for a single person and £20,200 for a family. If the level of the cap had instead kept pace with CPI inflation, it would be £17,233 for a single person and £25,720 for a family.

The SNP said this means that single people in Rutherglen and Hamilton West are £2,479 worse off a year, and families are £5,520 worse off a year, due to the cap not keeping pace with inflation.

Read more: What do Rutherglen voters think as by-election campaign gets underway?

SNP candidate for Rutherglen and Hamilton West, Katy Loudon, said: "Hundreds of the poorest families in Rutherglen and Hamilton West have seen their incomes slashed as a result of the Tory benefit cap.

“Michael Shanks must come clean over whether the pro-Brexit Labour Party is secretly planning to keep this cruel Westminster policy against Scotland's will.

"The SNP is the only party offering real opposition to Tory cuts - and real change with independence. In contrast, Sir Keir Stamer's pro-Brexit Labour Party is copying the Tories - and taking thousands of pounds away from families in Rutherglen and Hamilton West.

"Whether it's backing the two-child cap, bedroom tax or benefits cap - the pro-Brexit Labour Party has become a carbon copy of the Tories.”

Scottish Labour has been contacted for comment.