Referees will have the option of awarding 20-minute red cards for technical offences during the Autumn Nations Series, organisers announced on Friday.

The sport's global governing body World Rugby trialled the change in the Rugby Championship earlier this year, allowing a team to replace a red-carded player after 20 minutes in the sin-bin.

Importantly for the Autumn Tests, which pitch southern hemisphere teams against those from the north, match officials will also retain the ability to award a permanent red card for acts of foul play which are deemed deliberate and dangerous.

"The red card variation ensures that players deemed to commit deliberate and dangerous offences receive the full sanctioning, and subsequent disciplinary process, with the team being reduced to 14 men for the remainder of the game," Six Nations Rugby said in a statement.

"Referees will have the option to award a 20-minute red card for technical offences. This variation on the law trial will run throughout the Autumn Nation Series and differs to the standalone 20-minute red card proposal due to be discussed by the wider game later this year."

National unions in South Africa, Australia and New Zealand back the proposal.

But there are others who oppose it, notably France and Ireland. The latter country's union said on Friday it did "not support the permanent adoption of a 20-minute red card," as proposed by World Rugby.

"Player welfare and safety are paramount to the core values of the game and the option of a permanent red card for deliberate and intentional acts of foul play supports those values and protects the integrity of the game," the Irish union said.

"The IRFU welcomes the variation to World Rugby's closed law trial," it added.

Other law trials on show in November include kickers having just 60 seconds to complete a penalty or a conversion, the latter with a countdown starting straight after a try is scored.

If a player exceeds this time limit, the conversion kick will be disallowed, while for a penalty, a scrum is awarded to the non-kicking team.

There will also be a scrum and line-out clock, with the set-pieces to be formed within 30 seconds of the referee and assistant officials making the respective mark. (AFP)