England defence coach John Mitchell does not believe New Zealand would benefit from seeing what England are up to in training.
John Mitchell wished New Zealand good luck if they want to spy on England ahead of the Rugby World Cup semi-final but says it would not give them an advantage.
England head coach Eddie Jones claimed someone was spotted filming England's training session on Tuesday.
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Jones said it may have been a Japanese fan seen in an apartment overlooking the pitch, but admitted he used to spy on opponents.
Defence coach Mitchell does not believe the All Blacks would gain anything from seeing how England were preparing for a titanic battle in Yokohama City on Saturday.
"If that is what they want to do, and that is the way they want to prepare, good luck to them," the New Zealander said.
He added: "We just happened to be training where there are apartments above our tiny two-metre fence, so I am not sure about what the use of the tarpaulins are.
"The facilities have been excellent but it's an area where people live and there is the odd red light around. There was one up in the corner, which was a bit suspicious.
"It doesn't really worry me. This game is so dynamic now so I don't see any advantage in spying on a team."
Mitchell revealed spying is not uncommon at the highest level of rugby.
"When I took over the All Blacks in 2001 we had a manager who was highly military and he loved surveying the whole area," he said.
"To me, you can get too involved in it and create an anxiety in your group. There is enough pressure at this level without chasing around some blokes that might be in a building with a camera.
"I was with Sir Clive Woodward when we were going for a Grand Slam against Scotland and we chased somebody from one of the papers around the corner and caught him in a hedge.
"He was pretty unlucky actually but that was when the game was a lot different to what it is now. I've seen coaches spy, I've had other coaches spy. I've had mates spy as well, but I don't see any advantage."