Exeter face a potential points deduction after admitting they broke Aviva Premiership regulations by fielding three overseas players against Leeds on April 3.
The issue centres on the registration of wing Nemani Nadolo, who was born in Fiji but registered under his Australian passport when he joined the Chiefs from Bourgoin in January.
Premiership clubs are only allowed to include two players from outside of Europe, Africa, the Caribbean and the Pacific islands in their 23-man match-day squads.
Exeter's Argentina fly-half Ignacio Mieres and New Zealand prop Hoani Tui were also in the squad for the defeat at Headingley.
All three players had also been named in the Chiefs squad that lost to London Irish on March 26, which was not picked up on at the time.
As a result, the RFU are understood to be treating both matches together as a single breach of the rules.
Exeter have been asked to provide all the paperwork to the RFU by tomorrow night and a disciplinary hearing is set to be convened later this week, probably on Thursday.
Exeter chief executive Tony Rowe has pleaded for leniency from the RFU.
The maximum sanction is a 10-point deduction, although previous cases of teams fielding ineligible players - including Sale, Wasps, Leicester and Saracens - have resulted in one or two point penalties.
Rowe said: "Unfortunately during our Aviva Premiership fixture away to Leeds Carnegie on Sunday, April 3, Exeter Rugby Club inadvertently included three foreign players within our match-day squad, when official rules permit us to only include two players.
"This was partly down to a clerical error on the club's part and we have now been asked by the RFU to submit to them our reasons for fielding three foreign players.
"We are aware this will need to go before a disciplinary panel, which is likely to be held later this week, and we intend to co-operate fully with the authorities over this matter.
"As a club we hope the authorities take into account our previous good record and there was no intention on our part to try and gain any kind of unfair advantage."
If Nadolo had registered under a Fiji passport he would not count as a foreign player but it is unclear whether he has one, having been raised in Australia.
The RFU first contacted Exeter last week, prompting the Chiefs to withdraw Nadolo from the squad that lost to Bath on Saturday.
The disciplinary panel will include representatives from both the RFU and Premiership Rugby.