Dupuy will miss the Six Nations
Stade Francais scrum-half Julien Dupuy has been banned for 24 weeks after being found guilty of eye gouging.
Dupuy, a French international, committed the offence on Stephen Ferris during his side's 23-13 defeat by Ulster at Ravenhill last weekend.
Prop David Attoub has been hit with an interim suspension pending the outcome of a reconvened hearing in January.
The Disciplinary Officer ruled that further evidence needed to be considered before a ruling was made.
Dupuy's six-month ban means that he will miss France's 2010 Six Nations campaign.
An ERC statement released on Friday said that the scrum-half's offence had been found to be "at the top end in the level of seriousness for an offence of this type".
However reacting to Dupuy's punishment, Stade president Max Guazzini denounced the ban as "excessive" and anti-French.
"It's excessive, very political and anti-French," said Guazzini from Brussels where the two sides meet again in the reverse fixture on Saturday.
"The ERC wanted to make an example of a symbolic player of Stade Français and of the French team which has never had a disciplinary problem.
"It's not normal that a private organisation in Ireland prevents a club employee from working, from playing. It is we who pay him."
France national coach Marc Lievremont has called on Stade to appeal against Dupuy's ban, which is scheduled to run until 3 June next year.
Ferris was the victim of more than one eye-gouging incident during the game
"We expected the worst and the worst thing has happened to Julien because six months is huge," said Lievremont.
"I hope there is an appeal and that the ban is replaced by something more reasonable."
The ban was imposed despite apologies by both players and the Stade club earlier this week.
The players apologised earlier in the week and were penalised by their club for their actions in the game on 12 December.
Television pictures showed Dupuy, the current first-choice scrum-half for France, sticking his fingers into the eyes of Ireland flanker Stephen Ferris late on in Saturday's game.
Ulster and Stade Francais are both level on nine points at the top of Pool Four and meet in the return fixture, being played in Brussels, on Saturday.
Thursday's hearing in Dublin dealt with the cases of two other French players, Brive duo Arnaud Mela and Guillaume Ribes.
Hooker Ribes was banned for four weeks for kicking an opponent in their 36-3 loss to London Irish, while lock Mela was banned for seven weeks for punching an opponent in the same game.
It is Mela's third ban for foul play in two years.
He received a three-week suspension for punching Steve Borthwick in a game between Bath and Albi two years ago and a four-week ban in January for striking Paul Emerick in a Challenge Cup game against Overmach Parma.