A question mark hangs over Nick Williams's future as an Ulster player.
A statement issued by Ulster Rugby has confirmed that they are holding an internal investigation into Williams's "alleged unauthorised absence".
It is understood that the back-row forward returned to New Zealand last week and subsequently missed Sunday's Pro12 win over Treviso in Italy.
The giant number eight will be unavailable for Friday night's game against the Dragons at Ravenhill.
Williams signed a contract extension with the Irish province in October, which secured his services until the summer of 2016.
The Kiwi has made a huge impact since signing for Ulster in June 2012 and his impressive performances last season led to him being named Pro 12 players' player of the year.
The New Zealander, 30, was also voted as Irish players' player of the season.
The barnstorming back rower has made 10 appearances for Ulster this season despite his availability being curtailed by injury.
"We all hope the process doesn't take long - for all parties concerned it's best that these things are dealt with immediately and then we can all move on," said Ulster coach Mark Anscombe.
Williams previously enjoyed a four-year spell with New Zealand Super 14 outfit the Blues, and also played for Ulster's Irish interprovincial rivals Munster.