The committee, chaired by Labour MP Tony Wright, has singled out Bell Pottinger Public Affairs, Luther Pendragon and DLA Piper as it presses ahead with its inquiry into lobbying. It has also called The Law Society to give evidence.
Bell Pottinger Public Affairs chairman Peter Bingle is expected to appear before the MPs on 6 March. It is likely that a representative of Luther Pendragon will be called in for the same session.
Both agencies have courted controversy by steadfastly refusing to join the APPC. However, both have also recently attempted to make amends by drawing up their own codes of conduct.
The committee also wants to hear from the lobbying arm of law firm DLA Piper, Global Government Relations (GGR). Founder and chairman Tim Clement-Jones is also Liberal Democrat spokesman on culture and sport in the House of Lords. In the APPC's eyes, this creates a conflict of interest - its code of conduct states that members must not employ sitting MPs or peers.
PRWeek understands that Clement-Jones will not be appearing before the committee. Instead, GGR will be represented by its head of media Eben Black.
As PRWeek went to press, the committee was due to hear from Lord Mayhew and Lord Maclennan of Parliament's advisory committee on business appointments.