England prop Joe Marler was issued with a formal warning by the Rugby Football Union on Thursday after posting an abusive tweet aimed at former Australia coach Bob Dwyer.
The 25-year-old Marler directed his fire at Dwyer for saying fellow Red Rose prop Dan Cole should have been heavily penalised for his scrummaging during England's 39-28 win over Australia in the first Test in Brisbane last weekend.
Marler on Tuesday tweeted an offensive word about Dwyer, then later deleted it, but the RFU has strict guidelines on the use of social media and the Harlequins prop was censured by Twickenham chiefs on Thursday.
It is not his first run-in with rugby officialdom -- World Rugby hit Marler with a two-game ban and £20,000 (25,000 euros, $29,000) fine for calling Welsh forward Samson Lee "gypsy boy" in a Six Nations international in March.
"Marler is extremely apologetic for the comment that was made and deleted it within a few minutes of it being posted on Twitter," said an RFU statement.
"The warning will be retained on Marler's disciplinary record for a period of five years and may be relied upon in any future disciplinary proceedings.
"The RFU considers this matter closed and will not be commenting further."
Marler, who was criticised by Dwyer for "illegal" scrummaging ahead of Australia's 33-13 victory over England at Twickenham in October which saw the hosts knocked out of last year's World Cup, ruled himself out of the tour of Australia after his troubled finish to the season.
Aside from the fine and suspension incurred over his remark to Lee, the 42-times capped Marler blotted his copybook immediately on his return when he was banned for two weeks for kicking a Grenoble player while playing for Harlequins in the European Challenge Cup.
England's victory in Brisbane saw them go 1-0 up in a three-match series with the Wallabies ahead of Saturday's second Test in Melbourne.