Ulster and Ireland have been dealt an injury blow after it was revealed Will Addison has suffered a setback in recovering from a back injury and will be out for "several months".

Addison has undergone surgery on the problem, with Ulster not stating a more concrete return date.

He will miss the remainder of this year's Six Nations and the November series.

Addison missed the World Cup because of a calf injury and had not featured since the restart.

Elsewhere Stuart McCloskey (elbow) and Billy Burns (calf) sustained injuries in the Heineken Champions Cup quarter-final game against Toulouse. They will miss the start of the Pro14 against Benetton at Kingspan Stadium on Friday.

Tom O’Toole will be unavailable for a period of several weeks because of an ankle problem.

Tom Stewart (hamstring) was injured in training on Monday and is currently unavailable.

Kyle McCall sustained a concussion in the recent Ulster 'A’ Inter-pro fixture against Leinster and will follow return to play protocols. Ethan McIlroy (ankle) was also injured during this match and, as a result, is unavailable for selection this week.