Security is being boosted at Christchurch's Hillmorton Hospital's adult in-patient unit after a series of assaults on staff.
In the latest incident a security guard was punched by a patient this morning and is in hospital after a brawl in the mental health unit.
Police were called to Hillmorton Hospital in Christchurch at about 9.40am this morning, to reports of someone being punched.
The person was then taken to hospital, police said.
A source confirmed to RNZ that the guard was assaulted after a brawl occurred.
The CDHB was already planning to meet with nurses this afternoon to discuss the issue of staff safety, after a string of serious assaults at the hospital.
Staff from Hillmorton will meet with DHB senior management later today to talk about safety after several recent assaults, including a patient throwing boiling water on a nurse, and a nurse being stabbed.
The number of accident compensation claims by mental health staff for assault injuries at the hospital leapt in the last year, with a jump of 20 more claims than the previous year.
Figures released by the Canterbury District Health Board show that in the year ending September 2018 the Accident Compensation Corporation (ACC) accepted 78 claims for injuries from assault.
The information released says this covers being hit, struck or bitten.
In 2017 the number of claims by mental health workers for assault had been 56, and in 2016 there were 59 claims.
In the last year ACC paid out $228,292 in medical costs and weekly compensation for staff following assaults.
Medical costs accounted for $44,314 of that amount, with the remaining $183,977 in weekly compensation.
In the year ending 30 September 2017 ACC paid out $350,172, with $299,261 of that paid out in weekly compensation.
In the year ending September 2016 $168,365 was paid out by ACC, with $40,614 in medical costs and $127,751 in weekly compensation.
CDHB chief people officer Michael Frampton said the wellbeing and safety of patients and staff was extremely important, and staff work extremely hard to maintain a safe environment across our services.
"The service has seen an unprecedented level of demand over the past five years," said Mr Frampton, "and we have also seen an increase in the number of injuries to our staff.
"SMHS (Specialist Mental Health Services) staff, management and clinical leaders, unions, supported by Canterbury DHB Health and Safety, work together to reduce the frequency and severity of incidents by actively addressing issues, strengthening clinical leadership, reviewing models of care, stabilising staff numbers, making environmental changes within buildings where we can, and strengthening induction and orientation procedures."
Today Canterbury District Health Board officials met with about 90 staff to discuss safety.
The DHB Chief executive David Meates conceded assaults at Hillmorton had been a problem for years, and two extra guards were being brought in, bringing the total number at the site to five.