Scotland fly-half Finn Russell will miss the Six Nations opener against Ireland after a "breach of team protocol", Scottish Rugby said on Thursday.
The Racing 92 stand-off will not play in Scotland's opener against Ireland on February 1 and it is unclear whether he will play at all in the campaign.
"Stand-off Finn Russell will play no further part in preparations for Scotland's Six Nations opener against Ireland, having been disciplined for a breach of team protocol during the week's camp in Edinburgh. He has returned to his club," a Scotland team spokesman said in a statement.
Reports in the British media claimed Russell had failed to show up for a training session after drinking the night before.
Informed he would not be selected for duty against the Irish, Russell was said to have opted to return to Paris and will not be among the travelling party who fly out for a warm-weather camp in Spain this Sunday.
Scotland host England in their second Six Nations fixture on February 8, looking to retain the Calcutta Cup for a third successive year, and coach Gregor Townsend has not closed the door on the former Glasgow star returning for that showdown.
The 27-year-old, who made his debut for Scotland in 2014, has emerged as a key figure in Townsend's side.
His potential absence for the entire Six Nations would be a huge blow as Scotland look to bounce back from a disappointing World Cup campaign last year.
The in-form Adam Hastings is now almost certain to wear the number 10 jersey in Dublin but Townsend may look for reinforcements with no other regular stand-offs in his squad.
Full-back Stuart Hogg did play there earlier in his career and Northampton centre Rory Hutchinson can also fill the position.
Scotland fly-half Finn Russell will miss the Six Nations opener after a breach of team protocol