http://news.bbc.co.uk/sport2/hi/rugby_unio...eys/8564375.stm
The Ospreys' Magners League match in Ulster on Friday, 19 March has been postponed at the Welsh side's request.
The region claim they do not have sufficient front-row cover to fulfil the fixture.
A statement from the Magners League confirmed the game has been called off and it is investigating the problem.
"This rule was introduced for health and safety reasons and Celtic Rugby could not sanction a match in these circumstances," read the statement.
"The reason for the postponement is that Ospreys are unable to supply suitably experienced front-row players in their match squad as is required under the Magners League rules and IRB [International Rugby Board] rules.
"Celtic Rugby recognises the great inconvenience this will have on Ulster and their supporters as well as Celtic Rugby's commercial partners, particularly BBC Wales who were due to broadcast the match live.
"Until Celtic Rugby has had the opportunity to review the matter there will be no further comment."
The Ospreys said they had never agreed to the 19 March date for the Ulster match, which was originally called off on 8 January because of the weather.
The region claim they did not want the 19 March date because they had already given the players and management leave between 12 and 22 March and had given Ulster three alternative dates which had been turned down.
And because of squad unavailability the Ospreys said they did not have any frontline players of sufficient quality to honour the fixture and were never prepared to use a significant number of players from their feeder clubs - Aberavon, Neath and Swansea.
But Aberavon's front row are facing frontline players elsewhere. On Friday night, the club will face an Ulster A squad in a British & Irish Cup fixture due to include frontline players Tom Court, Nigel Brady and Andy Kyriacou.
It is not the first time the Ospreys have been investigated by rugby authorities this season.
European Rugby fined the Ospreys 25,000 Euros for having 16 players on the pitch against Leicester in a Heineken Cup match in January.
Lee Byrne, who was fined 5,000 Euros, came on the pitch illegally.
And then the Ospreys were in the dock again over scrum-half Ricky Januarie's contract but were told they had no case to answer.
Both Ulster and the Ospreys have yet to agree on a new date for the match.[/b]
