The England wing was cited for a "lifting tackle" on Australian centre Berrick Barnes and he attended a disciplinary hearing in Sydney today.
Banahan has been suspended until 30 June, ruling him out of Saturday's second Test against the Wallabies and next Wednesday's clash with New Zealand Maori in Napier.
Banahan was unlikely to have been involved in Saturday's Test but he has started both of England's midweek games on tour and would have been in contention to face the Maori.
England have the right to appeal the suspension but no decision on that has yet been made public.
Martin Johnson will announce the England team to play the second Test tomorrow.
Mike Tindall missed training yesterday with a dead leg but Johnson is confident the Gloucester centre will be fit.
Meanwhile, Wales forwards coach Robin McBryde says flanker Gavin Thomas will probably not get a better time to push his World Cup credentials than in the upcoming Tests against New Zealand.
With Cardiff and British Lions openside Martyn Williams being rested and rising star Sam Warburton out with a broken jaw the Newport Gwent Dragon has the chance to make the number seven spot his own.
"Losing Sam was a bit of a blow, especially after how well he played against South Africa," said McBryde.
"On the back of that Gavin Thomas gets an opportunity.
"He's had a good back end of the season with the Dragons and thoroughly deserves his chance."
"At his age he's not going to get that many more, so I'm sure he'll be doubly keen to go out there and make a name for himself."