The IRB promised a revision of its disciplinary system after a one-week ban given to New Zealand's Adam Thomson for stamping.
Thomson is now set to miss the All Blacks' Test against Italy in Rome on Saturday but will be available to play against Wales and England in the remaining international fixtures of the world champions' European tour.
The back row forward, having been cited for "stamping or trampling" on the head of Scotland's Alasdair Strokosch during New Zealand's 51-22 victory at Murrayfield on Sunday was given a one-week ban by an IRB disciplinary hearing in London on Wednesday.
Former England hooker Brian Moore described Thomson's suspension as "ludicrously lenient".
And the punishment was in marked contrast to the eight-week ban handed out to Australia lock Rob Simmons by a separate IRB hearing in London earlier on Wednesday for a "tip tackle" on France flank Yannick Nyanga during the Wallabies' 33-6 defeat in Paris on Saturday.
Thomson, unlike Simmons whom the match officials at the Stade de France could not identify as the guilty party, did receive a yellow card at Murrayfield although Scotland coach Andy Robinson was not alone in thinking the forward had been fortunate to avoid being sent off.
Both Thomson and Simmons have a right of appeal.
IRB chief executive Brett Gosper, who took up his post in June, responded to Moore's comments and similar complaints on Twitter by saying: "The IRB will review this case as it is a match under our jurisdiction.
"If we decide to take action we will make it public," the Australian added.
Samoa centre Eliota Fuimaono-Sapolu slammed the Thomson verdict and compared it with the three-week ban he received from England's Rugby Football Union last year for tweets about Owen Farrell.
"I got 3 weeks for sarcastic tweets. So had I just rucked Farrells head I would have got only a week? Its just so comical these days," Fuimaono-Sapolu said.
Simmons, a replacement forward in Paris, received a ban of eight 'active' weeks' that took into account he was not scheduled to play immediately after the end of a Wallaby tour that sees them play England at Twickenham this weekend before Tests with Italy and Wales.
His suspension runs until February 24 and leaves Australia with just two fit locks heading into Saturday's Cook Cup clash at Twickenham.
Wallaby coach Robbie Deans is due to name the side to face England on Thursday.
"We're disappointed in the decision but I haven't had the opportunity to read the decision yet and obviously we'll do that before we settle on [whether] that's the end of the matter or not," Deans said.
With a second lock, Kane Douglas, already ruled out of Saturday's Test with a knee injury, Simmons's suspension increases the likelihood that Scott Higginbotham will be called into the squad following the end of his two-Test ban this weekend.
"We've maintained contact with Scotty, he continues to train and from the outset was hopeful that it wouldn't be the end of his tour prospects," Deans said.
"He's obviously a bloke who would have been here if he hadn't had that setback so he's high on our list."
Deans did not rule out calling for two replacements but said it would hinge on Douglas's recovery.
"If the medical staff believe it's marginal that he'll be available to us next week we'll probably have to act," he said.
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