Ireland fly-half Joey Carbery has been ruled out of the Six Nations after sustaining a wrist ligament injury while playing for Munster.

Carbery, who was injured in last week's defeat by Ulster, will be sidelined for two to four months, Munster coach Johann van Grann said.

Ireland take on Scotland in their Six Nations opener on 1 February.

Carbery's absence is a major blow with regular number 10 Jonny Sexton already a concern because of a knee injury.

On Monday, Leinster said Sexton was making "good progress" in his recovery from knee ligament damage.

Leinster added that Sexton would "increase his training load this week".

Munster lock and back row Tadhg Beirne has had ankle surgery after suffering the injury in the Champions Cup defeat by Saracens in December.

Beirne looks certain to be out of contention for Ireland's opener against Scotland but could be available before the end of the tournament.