England's RFU has warned Billy Vunipola over his conduct during an incident in Mallorca, Spain, which saw the back-row tasered, arrested by police and fined.
The event in question took place in late April, with Vunipola denying reports in Spanish media that he acted violently, while police said he was arrested for the crimes of disobedience and slapping a police officer.
Vunipola apologised "unreservedly" for his conduct in a statement at the time, and was fined €240 ($257).
Saracens, Vunipola's club, conducted an internal investigation with which the player cooperated and presented their findings to the RFU, the governing body for the sport in England.
"The RFU has reviewed the information Saracens provided following its investigation into the incident involving Billy Vunipola in Mallorca on 27 April, which resulted in the club issuing him with a formal warning.
"We have also considered the apologies Billy has provided, his clear contrition and the circumstances around the incident and have concluded the most appropriate course of action is to issue a formal warning under RFU Regulation 19.6.13. This warning will sit on his record for five years and may be relied upon in future disciplinary proceedings.
"It has been made clear to Billy that as a senior and respected player, such actions risk bringing the game as a whole into disrepute. In particular, such actions clearly go against the core values of rugby which collectively the sport works hard to promote."
Vunipola has made 75 appearances for England, most recently featuring in the narrow Rugby World Cup semifinal defeat to South Africa in October.
