World Rugby has commissioned an independent disputes committee to review the controversial end to Europe's World Cup qualification period.
The decisive match between Belgium and Spain will be front and centre of the investigation, with the world governing body "deeply concerned" about the deployment of a Romanian officiating team.
Romania needed Spain to lose to qualify for the 2019 tournament and referee Vlad Iordachescu infuriated the Spanish players with his decision-making as they crashed to an unexpected 18-10 defeat.
The Spanish Rugby Federation had asked Rugby Europe to appoint different officials but were turned down.
"World Rugby was deeply concerned about the circumstances surrounding the Belgium versus Spain Rugby Europe Championship match, a match that was decisive in the context of Rugby World Cup 2019 qualification," said a statement from the sport's governing body.
"Specifically, concerns related to the process and perception of Rugby Europe's appointment of a match official team that was not neutral in the context of qualification and failing to act on Spain's concerns in respect of the appointment.
"While recognising Rugby Europe's responsibility to review events in their own competition, given the context and significance of the fixture World Rugby acted immediately to request information relating to the above issues from Rugby Europe and participating unions."
World Rugby's executive committee and board had advocated a replay of the Belgium-Spain tie but unspecified issues around player eligibility appear to have clouded the issue yet further.
"Given this information concerns potential breaches of World Rugby regulations, and given the complexity and interconnectivity of the issues, a full and independent review is warranted," the statement added.
"This is in the best interests of the sport, teams and fans and is fully supported by Rugby Europe."
Rugby Europe has also convened an independent judicial panel into player conduct after the match in question, with disgruntled members of the Spain team appearing to confront Iordachescu as he left the field.