"We take matters of player conduct extremely seriously and have been happy with the professionalism and discipline of this squad in general terms," said Wales team manager Alan Phillips.
"Andy knows he has misbehaved and is apologetic, but he also knows that he must take responsibility for his own actions and accept the repercussions.
"This kind of behaviour cannot be tolerated in a professional, elite sporting environment and we have acted quickly and incisively in order to leave no ambiguity over the dim view we take of this situation.
"The player has made his private apologies to the Welsh management team as well as apologising in a public statement and we have also asked him to apologise to the Vale Resort Hotel, before asking him to leave the squad.
"We will now leave the South Wales Police service to conclude the matter and we will be making no further public statements at this time."
Cardiff Blues CEO, Robert Norster added;
"Following on from the surreal finish to the weekend's encounter with Scotland, the news of what appears to be a bizarre but serious lack of judgement by one of our players whilst on national duty is of real concern."
"It seems, albeit from a distance, to have been a prank that has somehow gone dreadfully wrong with potentially very serious implications."
"Consequently, we fully accept and respect the WRU's understandable and prompt action to address the issue. Naturally, as this is an ongoing police matter, we will also not be commenting further at this time".
A specific replacement for Powell will not be added to the Wales squad, although the inclusion of Scarlets hooker Ken Owens as cover for his injured regional colleague Matthew Rees (groin) and Blues hooker Gareth Williams (knee) means the squad retains 35 members.