APPC chair Gill Morris called the meeting this week after receiving a formal complaint concerning a number of breaches of the lobbyists code of conduct by Morgan Allen Moore.
Morgan Allen Moore strongly denies any wrongdoing. The complaint is thought to have been made by a disgruntled former employee with links to the Conservatives.
The agency's chair Steve Morgan ran the latter stages of Hain's controversial Labour deputy leadership campaign, hitting the headlines after it emerged that he made a £5,000 donation through a mysterious think-tank.
PRWeek understands that the complaint focuses on Morgan's donation to the Hain campaign and the use of Morgan Allen Moore offices by the campaign.
In particular, it is alleged that a number of cheques to Hain4Labour were sent to the Cardiff offices of Morgan Allen Moore before ending up in the campaign coffers.
These actions could breach section 12 of the APPC code of conduct, which states that lobbyists ‘must keep strictly separate from their duties and activities as political consultants any personal activity or involvement on behalf of a political party'.
The agency has insisted that Morgan acted in a personal capacity. Director Richard Moore described the complaint as ‘mischief-making by people that hold opposing political views'.
The complaint was filed from a private address under the name of James Davenport. It is understood that Davenport is an active Conservative who once worked for ex-Tory leader Michael Howard before spending three months at Morgan Allen Moore in 2001.
The APPC management committee will meet on 28 January to decide whether the complaint warrants further investigation. ‘We are looking in to this in a specially convened meeting,' said Morris.
Work and pensions secretary Hain this week declined a request from a Tory MP for details of his meetings with Morgan Allen Moore.