A Belgian Roman Catholic deacon who murdered at least five people, including his own mother, by injecting air into their veins, has been handed a 27 year prison sentence.

Ivo Poppe, 61, a former nurse, also killed his great-uncle by smothering him to death with a cushion when he was 22-years-old.

Prosecutors said during the trial that there could be up to 50 more victims after reports of many deaths in suspiciouss circumstances during the time he was working at the clinic, in West Flanders.

Dubbed the 'Deacon of Death' by Belgian media, Poppe was arrested in 2013 after he admitted to his psychiatrist that he had "actively euthanised dozens of people".

A jury found Poppe guilty of the murders of his 90-year-old mother, his 80-year-old father-in-law, two great-uncles aged 79 and 81 and another patient aged 79.

The married father-of-three, who worked at a hospital in Menen, in the 1980s and 1990s, was acquitted of a sixth murder charge, at the trial in Bruges.

Poppe told a court that he was "very sorry" for what he had done while his lawyer said he acted out of 'boundless empathy' with his victims, according to the Daily Mail.

The defendant said that his victims had not asked for help to die, but he wanted to make their deaths less painful.

"His clean record does not give him any credit. He committed his first act when he was 22-years-old, when he killed his great-uncle using a cushion," one prosecutor said, according to the Belga news agency.

Prosecutors had wanted Poppe to serve a life sentence saying he "clearly enjoyed his power over life or death".

But a number of mitigating factors - including Poppe's bad health having battled cancer, his difficult youth, and his small risk of re-offending - lead a judge to jail him for 27 years.

Poppe said he did not know exactly how many people he may have killed by injecting air into the patients' veins, causing fatal embolisms.

Due to Belgian law, Poppe may be eligible for early release in just six years, as he has spent three years in prison and convicts can ask for probation after serving a third of their sentence.