France prop Atonio set to miss Six Nations run-in with ban
Atonio, 32, was shown a yellow card in Saturday's defeat to Ireland following a high tackle on opposition hooker Rob Herring.
"The player admitted that he had committed an act of foul play worthy of a red card," the Six Nations said.
"Having acknowledged there were no aggravating factors and mitigating factors including the player's immediate admission of guilt, his exemplary disciplinary record and genuine remorse, the committee reduced the six-week entry point by three weeks, resulting in a sanction of three weeks," they added.
La Rochelle front-rower Atonio could have his suspension reduced by a week so as to be able to make his 50th Test appearance against Wales on March 18th if he successfully completes a coaching programme.