Rugby referee Chris Busby is set to retire from officiating following critical comments made by Mack Hansen which resulted in a ban for the Ireland international.

Busby was appointed an assistant referee for France v Wales and Italy v France in this year's Six Nations, but BBC Sport NI has learned that Sunday's Investec Champions Cup match between Bath and Clermont is expected to be his last as an official in the professional game.

Ireland wing Hansen will be suspended for three matches after criticising Busby and his officiating team in Connacht's loss to Leinster in the United Rugby Championship last month.

Hansen received a six-week suspension, three of which are suspended, meaning he will be available for Ireland's Six Nations campaign.

Hansen said the refereeing in the Aviva Stadium match on 21 December made it feel like Connacht were playing against "16 men".

As part of his sanction, Australia-born Hansen - for whom a lengthier ban would have impacted his availability for the Six Nations - must apologise to referee Busby and undertake "an appropriate course related to match officiating".

While personal reasons are thought to be at the forefront of Busby's decision, it is believed the Hansen episode was a factor.