NRL chief executive Todd Greenberg is set to come under fire with the ARL Commission launching an internal inquiry into last week's botched funding negotiations with the clubs.

ARLC chairman John Grant sent an email to all 16 club chairmen at 2.45am on Tuesday ahead of their meeting in Sydney, informing them of the commission's decision to ask Greenberg and NRL chief financial officer Tony Crawford for a "please explain".

In further evidence of the divide between the commissioners and the NRL executives, Grant has appointed finance guru Tony McGrath, who holds one of six seats on the ARLC, to oversee the NRL's revised offer to the clubs.

Grant and the commissioners maintain they were not informed of the proposal that was put forward to the clubs last week, in which Crawford outlined plans to delay funding over six years rather than the agreed five-year term.