Ireland prop Dave Kilcoyne has been ruled out of the Six Nations after his club Munster said he will be out for six months with a shoulder injury.

Kilcoyne has 56 Ireland caps and made four appearances off the bench in the Rugby World Cup last year.

He also featured in Ireland's Grand Slam win last year, earning his 50th cap in the thrilling win over France in Dublin.

Ireland begin their Six Nations defence against France in Marseille on 2 February.

Kilcoyne's injury absence - announced in a squad medical bulletin from Munster - adds to mounting fitness worries ahead of next week's Investec Champions Cup match against Toulon.

Jack O'Donoghue requires a scan on a knee injury he sustained in Munster's New Year's Day defeat by Connacht, while second row Edwin Edogbo and Diarmuid Barron also require surgery for Achilles and foot problems.

Munster head coach Graham Rowntree has an extensive injury list that includes Ireland flanker Peter O'Mahony, Joey Carbery and South African World Cup winners Jean Kleyn and RG Snyman.

Oli Jager and Eoghan Clarke are undergoing their return-to-play protocols after sustaining head injuries.