Former Georgia rugby captain Merab Sharikadze has been banned for 11 years over his role in a urine-swap scheme that helped several of his national teammates to cheat anti-doping tests.
It was also announced on Tuesday that another five players and a member of the support staff had been sanctioned by World Rugby, with bans issued of up to nine years.
A parallel investigation between World Rugby and the World Anti-Doping Agency was triggered when irregularities in urine samples were identified by the governing body's athlete passport management programme.
Sharikadze, 32, who made more than 100 appearances for Georgia, is the most heavily sanctioned for tampering with urine samples over an extended period before the 2023 World Cup.
The former skipper, who led Georgia to a famous win over Wales in Cardiff in 2022, was found to have provided 'clean' urine to three teammates.
Hooker Giorgi Chkoidze has been banned for six years, with Lasha Khmaladze, Otar Lashkhi and Miriani Modebadze receiving three-year suspensions, and Lasha Lomidze banned for nine months.
Nutsa Shamatava, a team doctor, was found to have provided advance notice of upcoming out-of-competition doping controls to players in group chats. She was banned for nine years.
The initial "operating hypothesis" was that the urine sample substitutions were conducted to conceal the use of performance-enhancing drugs but there was no evidence to support this.
World Rugby said: "In parallel, there was credible evidence to support the players' assertions that the urine sample substitutions occurred to conceal the use of non-performance-enhancing substances (namely, cannabis and tramadol)."
Sharikadze ended his rugby career shortly after a 2023 World Cup where Georgia finished bottom of their pool, changing sports to become an MMA fighter.
'SCANDAL FOR GEORGIAN SPORT'
The Georgia Rugby Union has also accepted a misconduct charge after several players and staff "wilfully failed to comply with their anti-doping obligations".
The union has now agreed to a financial penalty as well as anti-doping reforms.
"Our extensive four-year investigation has helped identify subversion of the doping control process and sends a clear message that World Rugby takes all anti-doping matters extremely seriously and is an unwavering champion of clean sport," said World Rugby chief executive Alan Gilpin.
WADA president Witold Banka said later Tuesday: "WADA welcomes the latest work concluded by World Rugby in what is a scandal for Georgian sport.
"The suspensions these individuals have received are significant and send a strong message to others who may be tempted to try and cheat the system."
WADA also said that, following talks, the Georgian government had withdrawn its recognition of the Georgian Anti-Doping Agency.
It added the government was working with WADA to establish a new national anti-doping body with "entirely different personnel to those in GADA".