"However, based on new information obtained as a result of the incident and follow-up assessment, that decision was reviewed and Zorb New Zealand Ltd was found to be covered by the regulations," the statement said.
"This new information relates to the downhill nature 'ball rolling' or Zorbing. WorkSafe found that these activities are designed to deliberately expose a participant to a risk of serious harm that must be managed by the operator, and relies on the operator having an effective safety management system in place.
"Without a safety system, this activity is likely to cause serious harm to a participant.
"Zorb New Zealand Ltd is now working towards registration as an adventure activity operator.
"Until it is registered, or is granted a temporary exemption, it cannot legally provide the downhill 'ball rolling/Zorbing' activity'," the statement read.
"We understand that the operator is working to meet the requirements of these notices, and a WorkSafe inspector is scheduled to visit Zorb New Zealand Ltd [today] to make sure they are on track.
"In order for the improvement notices to be lifted, Zorb New Zealand Ltd will need to satisfy the assessment inspector that adequate safety systems exist."
Zorb Rotorua general manager Haydn Marriner said the company was working on the issue.
"Zorb Rotorua has always operated legally and we are happy to be working with WorkSafe in order to become compliant," he said.
"We are in a unique position being caught between two worlds. Previously we were considered as a non-adventure activity, and now we are, so WorkSafe has asked us to cease operation until we are compliant.
"This could mean we are closed for a few days, or up to six weeks before we get an exemption."
Mr Marriner said Zorb Rotorua was closed yesterday and today for scheduled electrical upgrades, which happened to coincide with WorkSafe's decision to close it down.
He said he did not know when the operation would be up and running again.
That, he said, was in the hands of WorkSafe's auditors.
Ogo Rotorua, which runs a similar operation on the side of Mt Ngongotaha, has been registered as an adventure activity operator since November 2014, and continues to operate.