Tournament organisers European Professional Club Rugby (EPCR) have confirmed they will probe a mass brawl during Saracens' 15-6 Champions Cup victory over Munster.
The title holders' pool stage win at Allianz Park on Saturday came amid allegations that Munster's chief medic Dr Jamie Kearns made an offensive remark about England hooker Jamie George's weight.
EPCR announced on Sunday it is looking into "incidents" during the match and would seek the views of referee Pascal Gauzere and his officials and both clubs.
"EPCR has decided to investigate incidents which occurred during the second half of the Heineken Champions Cup, Round 4 match between Saracens and Munster Rugby at Allianz Park yesterday (Saturday, 14 December)," the statement said.
"Information will now be sought from the match officials and from both clubs and EPCR will be making no further comment until the investigation has been completed."
The brawl spread to the athletics track surrounding the pitch before order was finally restored.
Saracens' assistant coach Alex Sanderson later claimed his side's anger had been sparked by a comment from Dr Kearns about George.