The 31-year-old appeared in court after an incident at a bar in the island's capital Palma in which police tasered him.

Vunipola later issued a public apology and was fined 240 euros (£205) for resisting the law.

He has, however, escaped a fine and any ban from the RFU.

"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," an RFU statement said on Thursday.

The warning from English rugby union's governing body will remain on Vunipola's disciplinary record for five years.

Vunipola told the Daily Mail, in an interview published last week, that he had been drinking for the first time since 2022 in anticipation that it would be his final team-bonding trip with Saracens.

The number eight is set to leave the London club at the end of the season.

"My issue is just not knowing when to stop and that's probably why I stopped drinking for so long," he said.

Saracens had also given Vunipola their own warning after conducting an internal club investigation.

"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," the RFU statement added.

Vunipola is expected to leave reigning English champions Saracens, currently second in the table, at the end of this season and been linked with a move to French club Montpellier.

Vunipola has won 75 England caps, making his Test debut against Argentina in 2013.