The mother of an extremist inspired by so-called Islamic State who stabbed shoppers in a New Zealand supermarket said her son was radicalised by neighbours from Syria and Iraq who helped him recover from an injury.

The attacker, Ahamed Aathil Samsudeen, was a 32-year-old Tamil Muslim from Sri Lanka.

He arrived in New Zealand 10 years ago on a student visa, and applied for refugee status on the basis of being persecuted in his home country.

Samsudeen was shot and killed by police, who said five people were stabbed and two injured in last week’s attack.

His mother, Mohamedismail Fareetha, said his descent into extremism began after he fell several storeys from a building in 2016 while at university.

“Because he did not have anyone there, it was people from Syria and Iraq who helped him.

“It looks like they brainwashed him. Then he started posting on Facebook,” she said in a phone interview on Saturday with a local TV station from her home in eastern Sri Lanka.

“He changed only after going abroad,” she added.

Police first noticed Samsudeen’s online support for terrorism in 2016, and the following year he was arrested at Auckland Airport.

He was heading for Syria, authorities say, and was later released on bail.

“After being arrested in 2017 he talked less with us, it was about once every three months,” his mother said, adding that two of her other sons “were angry with him and scolded him”.

In a statement Saturday, her son Aroos said his brother “would hang up the phone on us when we told him to forget about all the issues he was obsessed with.

“Then he would call us back again himself when he realised he was wrong. Aathil was wrong again yesterday. Of course we feel very sad he could not be saved.”

In 2018, Samsudeen was jailed for three years after he was found with IS videos and knives, and the following year his refugee status was cancelled after authorities found evidence of fraud.

Immigration authorities tried to argue he should remain behind bars, but in July, Samsudeen was released.