The man, a member of Delta's Dunedin Greenspace team, was using a petrol-powered hedge trimmer while standing on a ladder when he lost his balance and fell backwards, a leaked company document showed.
''As he was falling, he reached out with his left hand to regain control of the petrol-powered hedge trimmer that was falling towards him.
''He missed catching hold of the handle and his hand contacted the cutting bar.''
The accident, which occurred on April 10, left the man with partially amputated middle and little fingers on his left hand.
It also prompted an internal investigation by Delta, and a report by the company to the Ministry of Business, Innovation and Employment.
Details of the incident were contained in an internal Delta newsletter from Delta chief executive Grady Cameron, a copy of which was obtained by the Otago Daily Times yesterday.
Mr Cameron told the ODT the company took all incidents seriously, but accidents as serious as the worker's were ''very rare''.
''We have had none in the last 12 months as serious as this incident.''
The results of a thorough investigation had been forwarded to the ministry, and the company awaited its response, he said.
The accident came as the Independent Taskforce on Workplace Health and Safety last month warned New Zealand's workplace safety record was ''not fit for purpose'' and needed to change.
It also came as the number of ''close-call'' incidents reported by Delta workers more than doubled in the same period, from 75 in March to 164 in April, the Delta newsletter said.
However, Mr Cameron told the ODT the reports were incidents in which no harm occurred, and were a way to identify potential hazards and improve safety.
''They are not a measure of harm, rather an opportunity to take preventive action. We encourage close-call reporting as these are free lessons for preventive safety improvement.
''The greater the number of close calls reported the better.''
Seen in that light, the increasing number of reports was ''an improvement'', he said.
Delta was already reviewing the implications of the findings of the independent taskforce's report, which could lead to further changes.
However, the company's safety performance over the past two years compared favourably with industry peers, Mr Cameron said.
