Ulster’s next two home Pro14 fixtures will be behind closed doors in line with advice from Northern Ireland’s chief medical and scientific officers.
Dan McFarland’s men face Dragons on Sunday and Glasgow Warriors on 9 November at Kingspan Stadium.
The decision will be reviewed ahead of the game at home to Scarlets on 22 November.
A trial of 600 supporters was carried out at Ulster’s Pro14 opener against Benetton on 2 October.
However, in line with the views of the views of the chief medical officer and chief scientific advisor in Northern Ireland, it has been deemed “unwise for large gatherings to take place at this time”.
The announcement follows from last week’s announcement, made alongside the IRFU, that all rugby activity below elite level in Northern Ireland will be suspended for four weeks.
A statement said Ulster Rugby and the IRFU “continue to be in proactive dialogue with government to secure the necessary hardship funding for the sport at all levels”.
Before the decision on fans ahead of the game against Scarlets, Ulster also face trips to Cardiff Blues on 2 November and Zebre on 16 November.