Eighteen New Zealand judges have been affected by what appears to have been a "short-lived gastro bug" while attending the annual Higher Court Judges conference last week.

All of the judges are now recovered or nearly recovered, a Judicial Office spokesperson says, and the effect on court sittings has been minimal.

"There were only three Court of Appeal sittings scheduled for this week and these either have been or are in the process of being rescheduled, as are one or two Wellington High Court sittings."

The cause of the sickness is unclear as is the exact nature or type of 'bug', the spokesperson says.

The conference, this year held at Chateau Tongariro from Friday to Saturday, was attended by 53 members of New Zealand's High Court, Court of Appeal and Supreme Court.