Winger Josh Adams has been released from the Wales camp and suspended for their first two Guinness Six Nations matches for breaching Covid-19 protocols.
Adams attended a family gathering on Sunday January 31 after the Wales squad was released from camp the day before.
The squad were tested for Covid-19 on Wednesday and all tests returned negative.
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“We are extremely disappointed with the breach and have acted robustly and swiftly to take all appropriate measures,” said Wales head coach Wayne Pivac.
“All players and management have received detailed briefings and education regarding our protocols, and everyone has a responsibility to abide by the rules.
“On this occasion, Josh has made an error of judgement, he made a mistake and he has shown immediate remorse.”
Adams added: “I would like to apologise unreservedly.
“When out of camp, at the weekend, I made an error of judgement. I attended a small gathering of immediate family to celebrate a family milestone.
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“It was wrong to do this. I’m aware that everyone needs to follow the rules and being in the public eye I have a responsibility to lead by example and I’ve fallen short on this occasion.
“I’d like to apologise to my teammates and to our supporters for my mistake.”
Wales begin their 2021 Championship campaign against Ireland on Sunday.