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The first six months of the new lower benefit cap has seen 68,000 families having their welfare cut for the first time, losing each around £50 a week.

The current cap applies to working-age adults and is £20,000 a year outside London and £23,000 in the capital, having been £26,000 across the UK.

Ministers said the cap, designed to cut the welfare bill and encourage claimants to move off benefits and into work, had proved a "real success".

But Labour called for an urgent review.

People working more than 16 hours a week are exempt.

Since the new lower benefit cap was introduced, only 8,000 households have come off it because they have moved into work - fewer than 10% of the families who have had their welfare cut in the last six months.

Most households are no longer capped for other reasons, including cuts to their overall benefit claim.

The new figures show that seven out of 10 households are single parents - most of whom have pre-school children.

The previous £26,000 cap was for families only while single people without children had a cap of £18,200.

'Real success'

A total of 10,000 capped households include a baby under one-year-old and 70% have a child aged five or under.

Work and Pensions Secretary David Gauke said the latest figures showed the benefit cap had been a "real success".

"It is right that people who are out of work are faced with the same choices as those who are in work," he said.

"But behind these figures are thousands of people who are now better off in work and enjoying the benefits of a regular wage."

However, shadow work and pensions minister Margaret Greenwood said an urgent review of the cap's impact and effectiveness was needed.

"Clearly, this government's decision to cut families' incomes does not amount to supporting them into work, especially given their total failure to provide adequate affordable childcare."

And charity Shelter called for the cap to be scrapped immediately, saying it was pushing families "to the brink of homelessness".