Ellis (right) turned Carter completely upside down during the incident
Leicester scrum-half Harry Ellis has been banned for six weeks for a dangerous tackle on Perpignan's New Zealand fly-half Dan Carter.
England number nine Ellis upended Carter, who landed on his head, during their Heineken Cup tie last weekend.
Ellis was given a one-game ban by his club on Wednesday but an independent committee sitting in Dublin has now handed him a more severe sanction.
He is banned until 25 January but Leicester are considering an appeal.
"We are very disappointed that what we saw as a clumsy tackle has been characterised by the panel as an offence at the top end of the range of offending," said a Tigers statement.
"We will consider an appeal in consultation with the club's lawyers."
Any appeal must be lodged within 72 hours of receiving the full written decision from the disciplinary committee chairman.
All Blacks star Carter, who has signed a lucrative seven-month deal with Perpignan, was making his debut for the club from French Catalonia.
Ellis, 26, who came on as a second-half replacement for Leicester, admitted the offence when he appeared before the committee in Dublin.
During the match he escaped being sin-binned or sent off by referee Alan Lewis.
Heineken Cup organisers ERC said in a statement: "After considering the evidence available, the independent disciplinary committee determined that the offence was of the top-end of the level of seriousness for a dangerous tackle."
Ellis was already going to miss the Premiership match against Newcastle at Welford Road this weekend after being banned by his club but he will now sit out the league games against Harlequins, Bath and Northampton.
He will also miss the vital Heineken Cup pool matches against Treviso and the Ospreys next month, although he returns two weeks before the start of the Six Nations.