The International Rugby Board has approved a new law trial where unions will be permitted to nominate up to eight substitutes in international matches.

This law will be used from the November internationals.

IRB says in any international match, out of the 23 players selected for any match day, three specialist front row players are required to be selected by each team.

This is so that on the first occasion that a replacement is required in each front row position, the match can continue with contested scrums.

The reserve front row players will wear jersey numbers 16-18, while the remainder of the players will take the 19-23 jumpers with forwards numbered before backs.