Tokyo - World Rugby said on Thursday they had apologised to a bar in the Japanese city of Kumamoto after a "disappointing" incident in which Uruguay players on a night out reportedly damaged property and tackled a staff member.
According to Japanese media, several members of the Uruguay squad had spilled drinks, punched walls and mirrors and even torn apart a stuffed bear. Two of the team reportedly tackled a member of staff at the bar.
World Rugby said in a statement it was "aware of an alleged incident involving members of the Uruguay team in a Kumamoto bar."
"The alleged matter is very disappointing and clearly does not align with the family spirit of the tournament, characterised by the special warmth of welcome between the fans, teams and Japanese public," it added.
"An apology has been made on behalf of the tournament and it would be inappropriate to further comment while the facts are being established."
Local news agency Kyodo said police were investigating the alleged assault and questioned the players said to be involved before they left the country with the rest of the team.
There was no immediate public comment from Uruguay, and their official Twitter feed made no mention of the allegations, featuring only images of the team arriving back home.
The Rugby World Cup, which began last month, has largely passed off without incident, despite some raised eyebrows in often-reserved Japan over the occasionally rambunctious behaviour of fans on public transport and elsewhere.