England are being investigated for an alleged breach of protocol in communications with matchday officials during Saturday's 33-13 defeat to Australia, World Rugby has announced.

A report in Australia states that two members of the coaching team approached match officials in the tunnel at Twickenham at half-time. The loss to the Wallabies meant the hosts were dumped out of the tournament with one pool match still to play.

“World Rugby is investigating an alleged breach by the England coaching team of the match-day communications protocol between match officials and team members or union officials during the match between England and Australia,” a World Rugby Statement read.

England trailed 17-3 at half-time of the match and as the teams ran off the pitch, the coaches are reported to have spoken to officials in contravention of regulations.

“The protocol prohibits certain conduct on match days including coaches approaching match officials during a match or at half-time during a match,” World Rugby’s statement continued.

England are already facing a possible fine for their failure to fulfil media obligations for the mixed zone after the defeat by the Wallabies.

Meanwhile, Kyran Bracken has defended Billy Vunipola over comments attributed to the number eight, but at the same hinted at the extent of Andy Farrell's influence within England's coaching team.

Bracken hosted a charity Q&A staged last Thursday in which Vunipola is reported to have said he has never been coached by Stuart Lancaster, only Farrell, and that there was extensive opposition to the presence of Sam Burgess in the squad.

Vunipola has dismissed the comments as “laughable” and while World Cup winner Bracken insists they were taken out of context, he highlighted Farrell’s presence within England’s coaching team.

"David Campese, an Australia legend and a Pommie basher had great fun taking the mick out of England and Sam Burgess and all that sort of thing," Bracken told BBC Radio Five Live.

"While Billy Vunipola had an opinion, it was taken completely out of context. We've all known that Andy Farrell is much more involved in the coaching than everyone thinks.

“In fact, Billy said he had a huge respect for Sam Burgess and the aura he has.”

Although Vunipola has issued a strong denial, Press Association Sport understands that the view reported was held among members of England’s World Cup squad.

Farrell’s influence in selection and tactics had been noted and the management’s determination to pick Burgess was divisive, borne out of the belief his union apprenticeship remained in its infancy.

England's World Cup performance will be reviewed once the tournament is over with the futures of the coaching team and English RFU chief executive Ian Ritchie in grave doubt.

Bracken does not see how Lancaster and his lieutenants can continue in their roles.

“It’s a results business and we failed to qualify for the quarter-final of our own World Cup. That’s huge,” he said.

“Moving forward, I’m not sure how Stuart can still be involved as a coach knowing what’s happened: the failures of four Six Nations when we’ve finished second and then being knocked out of the World Cup.

“I’m not sure how they (the coaching team) can recover from that. The failure to qualify for the quarters is catastrophic. We’ve come up short badly against Wales and Australia.”