New Liberal Democrat leader Nick Clegg has launched a commission tasked with investigating Britain’s low levels of social mobility.

The group will look at the reasons progress in the UK has “stalled” and whether recent public spending increases can be expected to make a difference in the long-term.

Last month researchers from the London School of Economics and Surrey University found children born in poverty in the UK today are as likely to improve upon their background as those born 30 years ago.

That places the UK at the bottom of an international league table for social mobility, a fact Mr Clegg finds “utterly unacceptable”.

“I want to know why it is that Britain’s low levels of social mobility compare unfavourably with almost every other developed nation,” he said.

“Children should be free to realise their aspirations and not be held back by the circumstances of their birth.”

The Commission on Social Mobility, to be chaired by former Home Office permanent secretary Martin Narey, will publish its findings by the end of the year.

Mr Narey said: “The very high levels of child poverty in the United Kingdom are already deeply concerning. But the evidence of reducing social mobility is particularly alarming because of the potential for a child’s life chances to be determined – much more than in the ’50s or ’60s – by the circumstances of his or her birth.”

The government believes recent declines in social mobility have been halted thanks to a range of initiatives boosting educational attainment in the nation’s schools.

Its Children’s Plan, announced last month, laid out a range of further improvements including better parental engagement in a child’s education.