The Blairite outrider, long-touted as a potential anti-Brown Labour leadership candidate, will advise the Prime Minister

Alan Milburn made a surprise return to the political front line today as an advisor to Gordon Brown.

The Prime Minister has turned to the former Cabinet minister, a leading Blairite with whom he has repeatedly clashed, to head a new commission on social mobility.

Mr Milburn will chair a panel of industry leaders charged with identifying and removing obstacles to people from disadvantaged backgrounds getting into the professions.

The initiative was described by the Tories as "class war" reminiscent of the Laura Spence affair - a reference to the Tyneside comprehensive schoolgirl who was rejected by Oxford University in 2000 to the dismay of Mr Brown.

Comparisons were drawn between Mr Milburn's latest appointment and the Cabinet return of Lord Mandelson in the October reshuffle.

Mr Milburn has a history of rivalry with Mr Brown in government and has voiced concern about Labour's strategy since Mr Brown's accession.

He has now been put in charge of drawing up recommendations on one of the Prime Minister's biggest priorities - widening the scope for people to achieve their potential.

Measures to promote social mobility are to be set out in a White Paper on Tuesday.

But ministers have identified limited access to the professions - such as law, medicine, the senior civil service, media, finance and the upper ranks of the Armed Forces - as a major obstacle.

Mr Milburn, MP for Darlington, will chair a panel of representatives from the professions who will generate proposals for what they can do to widen access in their sphere.

It will also report recommendations to the Government when it produces a policy statement in June.

Issues to be considered include financial obstacles to access and progression, the role of work experience and internships, recruitment practices and what can be done to encourage new applicants for certain jobs.

In an article for The Sunday Times, Mr Milburn said he would be trying to ensure that "the best people, regardless of their backgrounds, have a fair crack of the whip".

"This is the right time for the Government to make its core purpose creating an upwardly mobile society again," he said.

"While Gordon Brown has rightly made the immediate priority getting the country through the global economic downturn, the Government needs to take action now to prepare Britain for the opportunities that will arise in the future."

Mr Milburn said Labour had made progress since 1997, but added: "While the glass ceiling in British society has been raised, it has not yet been broken. A renewed drive is needed."

He went on to say that the shifting world economy meant the professions needed to take advantage of all the talent on offer in the UK.

"With 90% fewer unskilled jobs and 50% more professional jobs expected in Britain by 2020, our future success depends on unlocking the talents of all our people," Mr Milburn said.

But shadow work and pensions secretary Chris Grayling said: "This is all about Gordon Brown fighting Laura Spence-style class wars and internal Labour political manoeuvring, and nothing to do with the real root cause of social immobility.

"The Government should be concentrating on tackling endemic worklessness, educational failure and family breakdown - not chasing political gimmicks."

Martin Narey, the chief executive of Barnardo's, who has been chairing a social mobility commission set up by Liberal Democrat leader Nick Clegg, said: "Although any move to open up professions seen as elitist should be applauded, it is far more important for the Government to focus on reducing the inequalities in the education system.

"Children from poor and disadvantaged backgrounds all too often end up in the worst schools and achieve the worst results.

"Only if these inequalities are tackled will children from disadvantaged backgrounds be able to fulfil their potential and become the doctors, army officers and barristers of the future."

Innovation, Universities and Skills Secretary John Denham, himself a resigned minister who has been welcomed back to the fold by Mr Brown, said the Prime Minister was making the best use of all the talents Labour had.

"The Labour government is actually saying, if we've got people of talent and ability, it doesn't matter about history," he said.

"It doesn't matter about the past, let's use them effectively, because this country needs a government that is going to do everything that is possible to support businesses and families through the current difficulties."