A former nurse who murdered three patients by contaminating their intravenous drips with disinfectant was sentenced to life in prison on Tuesday by a Japanese court, according to local media, AFP reported.

During her trial, 34-year-old Ayumi Kuboki admitted to killing the patients in their 70s and 80s five years ago in a case that shocked Japan.

She had previously told police she may have killed 20 people over just two months, but later told prosecutors she could not comment on that during the trial.

The presiding judge at the Yokohama district court said he had considered handing Kuboki the death sentence, public broadcaster NHK reported.

"She said she regrets [her actions] and wants to pay for her crime. There's a chance she will be reformed, and I couldn't help but to hesitate over choosing a death sentence," the judge said.

Prosecutors had demanded a death sentence for Kuboki, but the nurse's lawyers reportedly argued that she suffered depression due to stress over the deaths of her patients, and had diminished capacity.