Quote: Future immigration from within the European Union needs to be more tightly controlled, Labour leadership contender Ed Balls has said.
Writing in the Observer, he said "too many" British workers had been affected by migration policies under Labour.
He called for temporary controls on the number of workers from Romania and Bulgaria to be extended.
He also criticised the coalition government for failing to address concerns about unskilled EU labour.
In a BBC Politics Show interview later, Mr Balls is also expected to urge more debate about policy in the contest.
David Miliband, another leadership hopeful, will also be speaking to the BBC to outline his proposed party reforms.
In his article, Mr Balls, MP for Morley and Outwood in West Yorkshire, said high levels of immigration under Labour had had an impact on the pay and conditions of "too many people".
Mr Balls said he was a "strong pro-European", but of the "hard-headed rather than romantic variety".
"There have been real economic gains from the arrival of young, hard-working migrants from eastern Europe over the past six years," he wrote.
"But there has also been a direct impact on the wages, terms and conditions of too many people - in communities ill-prepared to deal with the reality of globalisation, including the one I represent."
He added: "As Labour seeks to rebuild trust with the British people, it is important we are honest about what we got wrong.
"In retrospect, Britain should not have rejected transitional controls on migration from the first wave of new EU member states in 2004, which we were legally entitled to impose."
Unskilled labour
Four of the six hopefuls for the Labour leadership - Mr Balls, David Miliband, his brother Ed, and Andy Burnham - have agreed immigration was an issue that Labour did not adequately address during the recent election.
Labour should not have opposed transitional controls on migration from EU states in 2004, Mr Balls said.
And he goes further in his article, by calling for temporary controls on workers from Romania and Bulgaria to be extended.
He also said Britain needed to do more to boost skills, apprenticeships, innovation and jobs in every region.
He said he supported Turkey joining the EU, but only with continuing restrictions on unskilled workers, at least for an extended transition period.
And he called for another look at rules which allow unaccompanied migrants to send child benefit and tax credits back home.
Campbell backs Miliband
Mr Balls also criticised the coalition government's immigration policies.
He said its commitment to cap immigration from outside the EU did not answer concerns among the British workforce about being undercut by unskilled labour from eastern Europe.
This weekend, former foreign secretary David Miliband has been outlining proposals to reform the Labour machine, including creating a post of party chairman, to be elected by the membership.
Meanwhile, in an interview for the Independent on Sunday, Tony Blair's former spokesman Alastair Campbell gives strong backing to David Miliband, while criticising Ed Miliband. | 
