An NAO spokesman said the public- spending watchdog had been taking soundings from industry sources as part of a preliminary study. It approached local authorities and interested bodies, including the Royal Institution of Chartered Surveyors (RICS) and spoke to members involved with regeneration.
The NAO was told that EP's chief executive, Anthony Dunnett, a former banker, lacked the requisite property expertise. A member said: "The job was a bit of a poisoned chalice. It would have been a tough job for any individual."
Trevor Beattie, head of policy at EP, said: "It's not for me to pre-empt the NAO's work but there is a distinction between what it is told and its conclusions." Last year EP claimed to have created and "safeguarded" 24,200 jobs and reclaimed 1,100 hectares of derelict land.
However, there is scepticism over the extent of the regeneration claimed. Nigel Smith, chair of the RICS land use and planning panel, circulated a paper to the RICS regeneration group recently, describing the claims as "out with the fairies".
The paper said: "Where projects are multi-funded by, say, the single regeneration budget, English Partnerships and European and Lottery funding, everyone claims the outputs. It's time we stopped deluding ourselves and started looking at the quality of outputs rather than meaningless numbers."
Others in the regeneration industry share his concern. Andrew Carter, regeneration adviser at Greater London Enterprises, said: "A lot of double counting goes on." However Mr Beattie, on behalf of EP, denied this and said: "We're not double counting. We maximise the output for every penny without exaggerating."
The NAO will decide over the next month whether to go ahead with a full investigation.