Health officials were investigating after paramedics used an ambulance – to take garden waste to a recycling centre.
Two paramedics in green uniform were seen removing at least ten sacks of garden waste from the back of the emergency vehicle.
The ambulance crew, wearing identification, skipped others waiting in the queue to dump the bags at the tip in St Austell, Cornwall.
Officials have confirmed the ambulance had been used ”inappropriately” during a scheduled break last Friday.
Onlooker Matthew Chubb, 27, an IT worker, said he ”couldn’t believe his eyes”.
He said: ”I know what I saw – it was an NHS ambulance – it had the NHS direct number on the back of it.
”I took down the registration – I was livid. It was a total misuse of an emergency vehicle.
”To make make matters worse, they decided to skip the queue and go straight to the front while everyone else waited their turn.”
A spokesman for the South Western Ambulance Service said: ”We can confirm that the vehicle seen on June 4 was part of our fleet.
”The crew were not booked on duty at that time, but were on one of two compulsory 30 minute unpaid rest breaks they must take.
”However, the trust acknowledged that their presence at this location was neither appropriate nor acceptable.
”An investigation is under way to determine how and why this situation occurred.
”The trust prides itself on delivering first-rate care to patients and is one of the best performing ambulance services in the country.
”The trust take things of this nature very seriously however and would like to make an assurance that the matter will be investigated thoroughly.”