The Northampton prop, Brian Mujati, faces a six-month ban after being cited for allegedly pushing the referee, Nigel Owens, in the back during the Heineken Cup defeat at Perpignan last Friday.

The Saints were stunned by today's citing by the Irish match commissioner, Murray Whyte, saying that no complaint had been made after the match and they were playing the tape of the game to see what the tight-head had been accused of. Mujati, a second-half replacement, joined Northampton in the summer from the Stormers and has won 12 caps for South Africa.

The 25-year-old has been charged with an act contrary to good sportsmanship. Under International Rugby Board regulations, he faces a minimum 24-week suspension if he is found guilty with a life ban the maximum punishment available for the disciplinary committee that will consider the case at a date yet to be set.

Neil Back received a six-month ban for shoving the referee, Steve Lander, at the end of the 1996 cup final between Leicester and Bath at Twickenham, while the former South Africa full-back, Percy Montgomery, was banned for two years, 18 months of which was suspended pending good behaviour, for pushing a touch judge to the ground while playing for Newport at Swansea in 2003.

Mujati scored one of Northampton's two tries in the 29-13 defeat at Stade Aimé Giral and the night could prove even more costly for the Saints because White also cited their second row, Juandre Kruger, for allegedly stamping on the home scrum-half, Nicolas Durand.