A mother has been jailed for 13 years for suffocating her two children aged 3 and 6 to death with helium, a gas that is used to make party balloons rise up into the air.

The mum, who has been named in local media reports only as Johanna E., 36, due to strict local privacy laws, used helium in a bag that she placed over the heads of her sleeping children Mia, 6, and Lio, 3, in their bedroom, suffocating them to death.

The incident took place in Oberstadion, which is a city in the south-western German state of Baden-Wuerttemberg, on the night of 26th April.

The defendant, who worked as the director of a nursery school, according to local media outlet Bild, is then said to have driven to the banks of the River Danube with the intention of plunging into the water, but she is said to have changed her mind.

She was sentenced to 13 years in prison by the Ulm Regional Court on 16th December. She was spared a life sentence because she suffers from “severe suicidal syndrome” and because she confessed to the crimes.

Her lawyer, Wolfgang Tresenreiter, 55, said that Johanna E. saw no other way out of her marriage, described as a “private hell”, because her family was devout and would not have accepted her divorcing her husband, who has not been named.

It is unclear if the sentence is final or whether it can be appealed.