Marler called Wales prop Samson Lee "gypsy boy" during the match at Twickenham last Saturday and on Wednesday Six Nations Rugby said no further action would be taken against him.
The governing body of the global game released a statement late on Thursday, however, in which it said it "noted" the outcome of the investigation.
"World Rugby can confirm that, in accordance with its regulations, it has requested further information from Six Nations Rugby in respect of the process that led to its decision," it continued.
Six Nations Rugby, in its ruling, accepted Marler had made the comment "in the heat of the moment", while the player said he "deeply" regretted the incident and had apologised to Lee at halftime of the match.
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The 25-year-old forward has been warned by England coach Eddie Jones about his conduct and earlier on Thursday was dropped from the starting line-up for this weekend's match against France.
Australian Jones said the decision to bench Marler for the Paris clash, in which England will be looking to secure a first grand slam since 2003, was not related to the incident.
Jones and his Wales counterpart Warren Gatland have been criticised for using the word "banter" to describe Marler's comments. Gatland has apologised.
(Writing by Nick Mulvenney; editing by Ian Ransom)
