Former Wales international Alix Popham has slammed the decision to allow Tomas Francis and Owen Watkin to continue playing at Twickenham on Saturday.
In the first half of Wales' defeat to England, Francis and Watkin were both involved in a heavy collision that left them appearing to be struggling for balance on the field.
Blood poured from a cut on Watkin's head as he struggled to get to his feet, while Francis was seen leaning against a post for support.
Watkin was immediately removed from the field to have his cut tended to and he underwent a head injury assessment (HIA). But Francis was preparing for the next phase of play, a scrum near Wales' line, before the referee told him he had to leave for a HIA.
Both players returned to the field 10 minutes later.
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Popham was diagnosed with early onset dementia two years ago and his doctor believes he suffered 100,000 sub-concussions in his 14-year career.
The former back-rower is angry at what he witnessed on Saturday.
"At first attempt he [Francis] couldn't get up and it wasn't just Tomas Francis, it was Owen Waktin as well," Popham told BBC Radio Wales.
"They were both laid out on the floor and were having some serious issues. For him [Francis] not to go off straight away and stay off... and that's the important thing.
"For what they were showing on the pitch - they were having balance problems, clearly dazed and those signs on the pitch is a removal and they don't return.
"These rules are put in place for a reason and they need to be followed."
Following his diagnosis in 2020, Popham joined a landmark case against the Welsh Rugby Union, Rugby Football Union and World Rugby.
Popham and other former professionals suffering similar affects were seeking to bring legal proceedings against governing bodies over what they claim was a failure to protect them from the risks caused by concussions.
When asked if he was disappointed with what he saw on Saturday, he replied: "Yeah 100%. On the biggest stage, a Six Nations game, when everything was to play for, the pressure is on the players and they want to stay on.
"But it was totally obvious. They were both sparked out on the floor and for them to stay on until the 60, 65th minute - it's criminal."
Lobby group Progressive Rugby, which is made up of a number of former and current players, as well as medical experts, described what unfolded as "a clear and flagrant breach of HIA protocol."
They say Francis should never have returned to the field and that the symptoms he displayed immediately after the concussion met the threshold for an immediate removal.
WalesOnline understands that Wales' medics were unsighted at the time of the collision and requested a video review of the incident with the independent match doctor.
That video review took place and led to Francis' removal from the field before the game restarted. The independent match doctor then conducted the HIA, which Francis passed. The tight-head prop also passed another HIA post-game.
The Welsh Rugby Union have not commented on the incident.
WalesOnline asked Wales boss Wayne Pivac about it in the immediate aftermath of the game and he said: “They go through some testing behind the scenes. They both passed the testing so they’re allowed to play on. They’ll go through more testing after and if they clear that, they’ll be allowed to train.”
Six Nations bosses are now reviewing the circumstances of what happened.
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