Video referees will be introduced in professional rugby union from next month when the game's governing body bows to pressure from clubs and unions to follow rugby league and cricket by using technology to help match officials determine whether a score should be allowed.

The World Cup contained several disputed tries, and a call was made for video referees to be included in the raft of experimental law changes that came into force this month, but the International Board (IB) wanted to wait until its annual meeting next month to make sure the wording of the fifth official's job description was unambiguous.

The video referee, who will operate only at games where the cameras are present, will be used to determine whether a try or a kick is legitimately scored, but his powers will be limited to the act of scoring; if television replays show there was an infringement in the build-up it will be beyond his remit. As in rugby league, the decision will be flashed up on screen.

The IB is also looking at substitutions, with matches now afflicted by numerous changes in the closing minutes. Under current rules, teams may use up to seven substitutes, but there are proposals to limit both the numbers who sit on the bench and those who are allowed on as replacements.