England hooker Dylan Hartley has been cited for allegedly biting the finger of an opponent.
Hartley, who could land a maximum ban of four years, will face a disciplinary hearing following the first-half incident during Saturday's RBS 6 Nations game against Ireland.
It is understood that Hartley is alleged to have bitten the finger of Ireland flanker Stephen Ferris in the 23rd minute.
In a statement, the Six Nations said: "England hooker Dylan Hartley has been cited following the RBS 6 Nations match between England and Ireland at Twickenham on Saturday for an alleged biting offence.
"The independent Six Nations citing commissioner for the match, Alberto Recaldini (Italy), cited the England player under IRB Law 10.4(m), "Acts contrary to good sportsmanship", for allegedly biting the finger of an opponent in the 23rd minute of the first-half."
The statment continued: "The player's hearing will be held by an independent Six Nations disciplinary committee at a date to be confirmed."
A biting offence carries a low end entry point of a 12-week suspension, with 18 weeks for mid-range and 24+ weeks at the top end in the IRB's disciplinary sanctions table.
The maximum sanction is a four-year punishment. If Hartley is banned, he could easily be ruled out of England's three-Test tour to South Africa in June.