England prop Joe Marler has risked sanction from the Rugby Football Union after using social media to direct an obscene remark at former Australia coach Bob Dwyer.

Marler used Twitter to call Dwyer a w****r in response to his claim that Dan Cole scrummaged illegally in the first Test against the Wallabies last Saturday. The tweet was quickly deleted.

The RFU has strict guidelines on the use of social media and Marler, a member of the Elite Player Squad, now faces a reprimand.

“How anyone could have allowed Dan Cole to scrummage the way he did was absolutely beyond me,” Dwyer had said after England’s 39-28 win in Brisbane.

Marler, who ruled himself out of England’s tour to Australia following a troubled end to the season, responded to Dwyer on Twitter.

“Bob Dwyer is a w****r,” Marler wrote on his official Twitter account.

Marler himself was accused of scrummaging illegally by Dwyer during the build-up to last autumn’s crucial World Cup group game against the Wallabies.

England subsequently endured a torrid day at the set piece, but having dispatched Australia in the first Test last weekend they could clinch an historic series victory Down Under if they prevail in Melbourne on Saturday.

Marler was fined £20,000 and given a two-week ban for calling Wales prop Samson Lee "gypsy boy" during the Six Nations game between the two sides.