Toulon said on Saturday they were considering appealing the decision to award the Scarlets a 28-0 European Champions Cup victory, 24 hours after the French club pulled out of the fixture due to coronavirus concerns.
On Friday, less than two hours before kick-off, the three-time winners refused to play the match at Parc y Scarlets after claiming Covid-19 "sanitary conditions were not met".
A member of the hosts' squad tested positive for the virus after last Saturday's trip to Bath and the player was put in self-isolation.
He was not picked for the meeting with Patrice Collazo's away side.
"EPCR (European Professional Club Rugby) didn't arbitrate, during the week before the match, the health situation connected to the meeting with the two clubs and only did so some hours before the meeting," Toulon said.
"It forced us into a harrowing decision.
"Toulon consider the decision taken by EPCR as irregular and are studying all possibilities of an appeal."
Tournament organisers European Professional Club Rugby (EPCR) said the Top 14 side had refused the chance to play the match later in the weekend.
The victory takes the Welsh region up to fourth in Pool A and gives the French club a mountain to climb to reach the quarter-finals with just two group games to play.
Three other games had already been cancelled this weekend with Lyon, La Rochelle and Toulouse awarded 28-0 victories against Glasgow Warriors, Bath and holders Exeter Chiefs respectively.
Two matches in the second-tier European Challenge Cup were also called off as Agen and Cardiff Blues were handed wins over Treviso and Stade Francais for the same reason as the cancelled fixtures in the Champions Cup.
- Munster stun Clermont -
Elsewhere, Clermont suffered just their second home pool stage defeat in the competition since 2008 as Ireland back-rower CJ Stander claimed a late try in Munster's 39-31 win.
The hosts led 28-9 after 25 minutes before full-back Mike Haley and replacement hooker Kevin O'Byrne put their names on the scoresheet for the two-time winners.
Later, Argentina winger Santiago Cordero celebrated a two-year contract extension with a hat-trick in Bordeaux-Begles' 47-8 hammering over the Dragons.
Earlier, joint record four-time winners Leinster went top of Pool A by overcoming a much-changed Northampton Saints 35-19.
Gloucester's 20-year-old substitute George Barton scored after four minutes of additional time to claim a 38-34 success over Ulster in the Cherry and Whites' first match since Danny Cipriani's midweek departure.
On Sunday, last season's runners-up Racing 92 head to Harlequins and Pat Lam returns to Connacht with his Bristol Bears, who lifted the Challenge Cup in October.
On Friday, Wasps' hooker turned No. 8 Alfie Barbeary claimed a double as they edged Montpellier 33-14.