Perpignan could face sanctions from the International Rugby Board after playing banned hooker Marius Tincu in a league match.
The Romanian was handed an 18-week ban by an independent commission after he was cited for making conatact with the eye/eye area of Ospreys prop Paul James in the Heineken Cup - with the suspension upheld on appeal.
Perpignan were left angry at the ban - which runs to March 9, 2009 - and even threatened to pull out of the competition if it was not overturned.
And although Perpignan failed in their bid to see Tincu cleared, it seems they have ignored the ban by playing the 30-year-old for their Top 14 encounter with Castres on Saturday.
The IRB are now investigating the matter before deciding what action to take.
"The IRB has asked the Federation Francaise de Rugby (FFR) to submit a complete record of the events, decisions and procedures that resulted in the apparent breach of sanction and Tincu taking to the field against Castres Olympique," read an IRB statement.
"On receipt of the report the IRB will decide on the appropriate course of action."

England 6-19 New Zealand - Highlights
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Worcester 12-12 Bath - Gillies
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| Time | Fixture |
|---|---|
| Guinness Premiership | |
| Friday 27th November | |
| Guinness Premiership | |
| 19:45 | Sale vs Wasps |
| 20:00 | Newcastle vs Northampton |
| 20:00 | Worcester vs Saracens |
| Saturday 28th November | |
| 15:00 | Harlequins vs Gloucester |
| 15:00 | Leicester vs Leeds Carnegie |
| 17:35 | Bath vs London Irish |
| Saturday 5th December | |
| 15:00 | London Irish vs Worcester |
| 15:00 | Gloucester vs Newcastle |
| 15:00 | Northampton vs Bath |
| 17:35 | Saracens vs Sale |
| Sunday 6th December | |
| 15:00 | Wasps vs Leicester |
| Saturday 26th December | |
| 14:15 | Bath vs Gloucester |
| 15:00 | Leicester vs Sale |
| 15:00 | Worcester vs Northampton |
| Sunday 27th December | |
| 15:00 | London Irish vs Saracens |
| 15:00 | Newcastle vs Leeds Carnegie |
| 16:00 | Harlequins vs Wasps |
| Friday 1st January | |
| 15:00 | Sale vs Harlequins |
| 15:00 | Saracens vs Leicester |
| Saturday 2nd January | |
| 15:00 | Northampton vs London Irish |
| 15:00 | Leeds Carnegie vs Bath |
| 15:00 | Gloucester vs Worcester |
| Sunday 3rd January | |
| 15:00 | Wasps vs Newcastle |
| Friday 8th January | |
| 19:45 | Sale vs Saracens |
| Saturday 9th January | |
| 14:15 | Bath vs Northampton |
| Result |
|---|
| Guinness Premiership |
| Sunday 22nd November |
| Guinness Premiership |
| London Irish 11 - 15 Newcastle |
| Leeds Carnegie 17 - 24 Sale |
| Saracens 22 - 6 Wasps |
| Saturday 21st November |
| Northampton 26 - 17 Harlequins |
| Friday 20th November |
| Worcester 12 - 12 Bath |
| Gloucester 12 - 9 Leicester |
| Sunday 1st November |
| Newcastle 14 - 3 Worcester |
| Wasps 9 - 15 Leeds Carnegie |
| Saturday 31st October |
| Leicester 29 - 15 Northampton |
| Harlequins 9 - 9 London Irish |
| Bath 11 - 12 Saracens |
| Friday 30th October |
| Sale 28 - 23 Gloucester |
| Sunday 25th October |
| Saracens 21 - 15 Leeds Carnegie |
| Saturday 24th October |
| Gloucester 6 - 35 Wasps |
| London Irish 18 - 12 Leicester |
| Northampton 21 - 16 Sale |
| Worcester 22 - 26 Harlequins |
| Bath 16 - 27 Newcastle |
| Sunday 4th October |
| Leeds Carnegie 10 - 26 Gloucester |
| Wasps 20 - 15 Northampton |
| Newcastle 15 - 22 Saracens |
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