England have denied a conflict of interest after one of the officials for their NatWest 6 Nations clash with Ireland refereed a squad training session on Tuesday.
Marius van der Westhuizen will run one of the touchlines at Twickenham on Saturday with Angus Gardner taking charge of a match that could yield a Grand Slam for Joe Schmidt's newly-crowned champions.
It is common practice for officials to work with teams during international windows in a bid to help understanding of the laws.
Under World Rugby rules an official is not permitted to help out a team when they are due to referee an upcoming game involving that side but there is no rule prohibiting an assistant referee, in this case one of the touch judges, Marius Van der Westhuizen of South Africa, from overseeing a training match.
Angus Gardner of Australia will be in charge for the game.
The IRFU did not immediately return a call to RTÉ Sport for comment on the report.
Asked if using the South African was appropriate given his presence at Twickenham on Saturday, England defence coach Paul Gustard said: "Why wouldn't it be?
"So they (Ireland) will be questioning his integrity? You could see it the other way, couldn't you? What if it goes against us.
"He's an international referee. He is one of the best referees. You're asking someone to come in here and assist in training, give his viewpoint on things.
"It's no different to if someone from Ireland rang up to give his viewpoint on things. They have the same access. I see no issue with it at all.
"This had been long in the pipeline. It is all part of understanding different referees, how they referee things.
"We have a relationship with the English referees that assist us. The opportunity to get other foreign referees in to give their viewpoint in how they see things is important for our growth as a squad."
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