Lee Byrne is a British and Irish Lions full-back and has won 38 Wales caps
Wales full-back Lee Byrne will miss the Ospreys' Heineken Cup double header against Munster with a fractured thumb.
The Ospreys have publicly criticised Byrne for missing a Welsh Rugby Union medical appointment that would have shown how bad the injury was.
A statement read: "He then failed to report to a scheduled screening on his return to the Ospreys."
As a result "the medical team were not in a position to confirm a diagnosis of his injury until late last week".
Byrne was withdrawn from the Ospreys squad that beat Edinburgh in the Magners League last week at the 11th hour.
The British and Irish Lions star will be out for five weeks - the entire festive schedule - because of the injury, which he sustained in Wales' November defeat by New Zealand.
The 30-year-old will miss Sunday's European trip to two-time Heineken Cup winners Munster - and the reverse fixture at the Liberty Stadium the following weekend - as well as the Ospreys' festive Magners Leagues derbies with Scarlets and Cardiff Blues.
Byrne now faces a race against time to be fit for Ospreys' crucial final two Heineken Cup Pool Three fixtures against London Irish and Toulon in mid-January.
He is unlikely to be available for selection for an estimated period of five weeks from now
Ospreys physio Chris Towers on Lee Byrne's injury
The Ospreys statement read: "The Ospreys were unfortunately not in a position to confirm the severity of the injury at an earlier date, despite it being flagged up by the WRU, after Lee failed to attend a consultation with a specialist that had been arranged by the union.
"He then failed to report to a scheduled screening on his return to the Ospreys, meaning the medical team were not in a position to effectively confirm a diagnosis of his injury status until late last week.
"Hence he was named in the initial match-day squad for the Edinburgh match until the severity of the issue became clear."
Byrne, who is contracted to the Liberty Stadium region until the summer of 2012, has been linked with a big-money move to France at the end of the season, while Ospreys team-mate James Hook is set to join a French club.
Ospreys physio Chris Towers said: "We're now in a position to confirm the severity of the injury Lee suffered in the recent Test match against New Zealand, which kept him out of the Edinburgh fixture last weekend.
"Further investigations yesterday (Tuesday) confirmed a fracture at the base of the thumb - and in light of this he is unlikely to be available for selection for an estimated period of five weeks from now."
Byrne's injury is another blow for the Ospreys ahead of their two games with Irish giants Munster as the Welsh region are already without injured Wales wing Shane Williams, who is recovering from shoulder surgery, and experienced back-rower Marty Holah because of suspension.
Byrne had only just returned from a broken hand - sustained in Ospreys' defeat at Glasgow on 24 October - when he suffered his latest fracture against the All Blacks on 27 November.
He missed Wales' opening autumn international against Australia with his injured hand but returned in the defeat by world champions South Africa.
Byrne also played in the draw against Fiji before his try-scoring display in the 37-25 defeat by New Zealand - the game in which he suffered his latest setback.