World Rugby is to trial the use of two on-field referees in New Zealand's 2016 provincial championship.
The decision follows a review of the rules by rugby's governing body.
Each referee's responsibilities have not been specified but it is thought the second official will police a new offside line a metre back from rucks.
Two referees have never been used in rugby union before but Australia's National Rugby League has had two on-field officials since 2009.
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