THE boss of a welfare-to-work firm at the centre of police investigations over alleged fraud has quit as the Prime Minister's "Family Champion".

Emma Harrison said she did not want the probe, which has seen four ex-members of A4e staff arrested, to distract from the Government's efforts to help vulnerable families.

"I have asked to step aside from my voluntary role as Family Champion as I do not want the current media environment to distract from the very important work with troubled families," she said in a statement.

"I remain passionate about helping troubled families and I am grateful for the opportunity to contribute in an area where I have been active for many years."

David Cameron handed Ms Harrison the unpaid role of getting families back into work in December 2010.

Two police investigations are under way after irregularities were referred by the firm to the Department for Work and Pensions.

A4e said on Wednesday that two cases of nine referred to the DWP remained outstanding.

One, being handled by Thames Valley Police, involves four former members of staff. A second, also being investigated by police, involves a subcontractor.

The DWP decided there was no "malpractice" involved in the other cases, according to the company.

Mr Cameron has called for a "thorough" investigation of the cases. "It needs to get to the truth and then we can take into account its findings," he told MPs.

Earlier this month, Ms Harrison warned highly-vulnerable households risked being harmed by the Government's "populist" benefit cap.

Shadow work and pensions secretary Liam Byrne said: "Emma Harrison has done the right thing. But this is not the end – it's the start of the real questions about the Government's back-to-work contracts which are costing millions but are simply not getting enough people into jobs."

A4e has been criticised over large payouts to Ms Harrison and other bosses despite what some have called an "abysmal" performance record.