On night shifts last week, three out of four Darwin ambulance crews did not include a qualified paramedic, but St John Ambulance has defended sending trainees onto the streets.

The story emerged after an experienced paramedic posted a message online revealing there were several all-student crews covering Darwin that night.

St John Ambulance confirmed most of the rostered teams were comprised of students, but said it only happened because two senior paramedics had been given the night off.

An ambulance spokesperson said they had been attending an event honouring their recent service in The Philippines.

Operations director Michael McKay says he and two other authorities were on-hand last Friday night to support the students.

“We rostered additional intensive care paramedics on ... to offer support for those crews and also attend other cases as required,” Mr McKay told the ABC.

United Voice, the union for paramedics and other health professionals, said it was unacceptable.

United Voice Northern Territory secretary Matthew Gardiner said the students needed years more experience before being handed the massive responsibility.

“They are in training and it is a fairly long and intensive piece of training,” he said.

“They should always have a qualified paramedic with them.

“This is one of the things that we have raised with St John [Ambulance].

“[We need to] keep our qualified paramedics here in the NT so we can keep good skill mixes on the road and give the best possible service for the people of the Northern Territory,” Mr Gardiner said.