Thieves who stole catalytic converters from cars parked at a hospital have been described as the "lowest of the low" by one of their victims.

Ben Eagle’s silver Toyota Prius was one of two cars targeted within hours of each other at Ipswich Hospital on Tuesday afternoon.

He had left the vehicle in the Heath Road hospital’s visitor car park while he visited his girlfriend Katharine Matthews, 35, who was undergoing a knee operation and was in Levington ward at the hospital’s Garrett Anderson centre.

However, when the businessman, 31, returned and tried to drive away, his engine began roaring like a race car, so he called out an AA mechanic who quickly diagnosed that he was missing the catalytic converter.

When Mr Eagle looked underneath he discovered wires hanging down close to the exhaust where the catalytic converter should have been.

He said: “It is just unbelievable how low some people can go. I just don’t understand how people can do that in a hospital car park.

“It could have been a nurse, a doctor or a cancer patient that was targeted.”

He had not been aware of anyone acting suspiciously at the time of the incident, around 3.30pm, but said the hospital had been busy and somebody must have seen the suspects.

He said: “I can only describe the sound as ‘really, really loud.’ When you don’t have a catalytic converter, it sounds like you are on a race track, but going really slowly.”

The other incident involved a Toyota Lexus and happened between 9am and 5pm.

A Suffolk Police spokesperson said police were liaising with the hospital in relation to CCTV of the areas where the crimes took place and would be conducting patrols.

Police advice for reducing such incidents includes installing alarms, lighting or CCTV, marking catalytic converters with etchings or spray paint to identify them, keeping vehicles in secure buildings and parking in a way that would make it difficult to access the converter.

Neill Moloney, managing director of East Suffolk and North Essex NHS Foundation Trust, which runs Ipswich Hospital, said: “We take any incidents like this on our sites very seriously. We have CCTV cameras in place, but we have asked our staff to be extra vigilant, and our teams are supporting Suffolk police with their ongoing enquiries.”

Witnesses or anyone who saw suspicious activity in the car park at the hospital is urged to contact police quoting incident number 37/22196/22.