Cardiff Blues have confirmed that centre Owen Williams has suffered a "significant injury to his cervical vertebrae and spinal cord."
The 22-year-old, who has played four times for Wales, was injured playing for Cardiff Blues at the World Cup 10s on Sunday.
The region said that he underwent an operation on Monday to stabilise a fracture and is currently recovering in hospital in Singapore.
His family and Blues staff are with him in hospital, and arrangements are now being made to arrange his safe transfer home "at an appropriate time."
The region and Williams' family have also thanked hundreds of people who have offered messages of support.
More top news
A fine and dry day with some warm sunshine in the afternoon, especially in the east.
Parents are more concerned about the cost of sending their children back to school than the price of school holidays, according to research.
The Barclays report calculates regional scores based on gross domestic product, working hours and average house prices.