Ospreys coach Steve Tandy says there are "question marks" over the officiating in their 23-25 Pro12 defeat by Munster.
Munster lift themselves back to the top of the Pro12 with a hard-fought win against the Ospreys in Swansea.
Wales wing Alex Cuthbert is set to play for Cardiff Blues in the Pro12 against Treviso on Saturday as one of 13 players released to regions.
Ospreys sign Sale Sharks' former South Africa tight head prop Brian Mujati until the end of the season as injury cover.
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Munster return to the top of the Pro12 with a hard-fought win to end Ospreys' 13-match unbeaten run.
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