A senior ambulance officer used an intravenous line to give himself saline solution to get over his hangover.

Steve Wykes, a paramedic in Dargaville, gave himself the solution last year. Saline solution is typically used to counter dehydration.

St John said Mr Wykes was suspended and disciplined at the time of the incident, but was allowed to return to work shortly after.

Northern general manager Stephen Franklin said an inquiry found no evidence of drunkenness, but told the Dargaville News: "The person was dehydrated and hung over and was disciplined."

He said a St John officer visited the Dargaville station on the day Mr Wykes administered the solution but did not find any "overt" signs of drunkenness and said that Mr Wykes had performed well on a callout.

Mr Franklin said he was satisfied that the issues were investigated correctly and that appropriate disciplinary action was taken.

However, Mr Franklin said: "It does concern and sadden me that some inappropriate behaviour has occurred."

A St John spokeswoman said last night that talks were under way between St John and the National Distribution Union to introduce a drug-testing policy.

Mr Franklin said he wanted to reassure members of the public and patients that procedures and checks were in place to ensure the safe storage and handling of all drugs.

Other alleged incidents in Dargaville have also been put to St John's management, including claims by ambulance volunteers that they have been bullied.

A female volunteer told the Dargaville News that a bloody cloth - which had been used to dress a patient's wounds - was thrown at another ambulance worker's face.

"There could have been blood from cleaning the girl's wrists," the volunteer said.

"It could have been a death sentence if that person had Aids."

St John said the claims were speculative but all complaints were taken seriously.