Nick Clegg has claimed "birth has become destiny" for many youngsters as he set out the Government's strategy to improve social mobility.
The Deputy Prime Minister, who admitted he had benefited from a privileged upbringing, insisted it was time to break down barriers preventing poorer children reaching their potential.
"It just is not right that for too many young people, birth has become destiny, that the circumstances of someone's birth should shape, narrow and limit opportunities at school, at college, at university, the labour market - and more than that, on some evidence, limit the length of time you will live," he said.
As part of a new social mobility strategy, he called on companies to allocate internships through open competition rather than being allocated to the "well-connected".
But he faced accusations of hypocrisy over his own intern experience at a Finnish bank, which was set up through a friend of his financier father.
Labour MP John Mann said: "It is total hypocrisy and really desperate for him to attack internships now. His policies are holding down social mobility in this country but he enjoyed all the advantages of family connections himself."
Campaign group Intern Aware also claimed that Mr Clegg's Liberal Democrats were among the "worst offenders" for unpaid internships.
Mr Clegg said the Lib Dems would be putting their own internship system "on a much more transparent footing" for youngsters, including making applications "name and school blind".
Prime Minister David Cameron called on MPs to recruit interns "from backgrounds who wouldn't always get those opportunities".
The Government will be tracking progress against its social mobility goals with the publication of a set of "indicators". Ministers are also setting up a Social Mobility and Child Poverty Commission, to be chaired at first by former Labour minister Alan Milburn.