The man who allegedly ploughed his car into pedestrians in Flinders Street in Melbourne on Thursday has been remanded in custody after a brief court appearance during which he covered his face with his hand.

Saeed Noori, a former Afghan refugee and now Australia citizen, was charged with 18 counts of attempted murder and one count of conduct endangering life after being formally interviewed by police on Saturday.

Noori was discharged from hospital on Friday and held in custody overnight awaiting an interview with police. Three people remain in hospital fighting for their lives following Thursday’s attack.

Noori, a 32-year-old man reportedly made comments about Allah and Asio in the lead-up to his interview with police.

He allegedly made “utterances” to police about voices, dreams and the “poor treatment of Muslims” to officers in hospital on Thursday night, as well as comments about Australia’s top security body and Allah.

“I think there was something, and I don’t know the exact detail, to do with Allah and some ramblings about Asio (the Australian Security Intelligence Organisation),” acting chief commissioner Shane Patton told the Herald Sun.

Police have said the alleged driver has lived in Melbourne for a number of years and had a history of drug abuse and mental illness. He was known to police from a minor assault charge in 2010 and was on a mental health plan.

Victorian police assistant commissioner Stephen Leane said he believed it was a “deliberate” act, and that Noori could be charged on Saturday.

“The motivation for that act we’ll work through. Our investigators will charge him with appropriate offences, if that’s what’s going to happen today.

On Saturday Victorian premier Daniel Andrews confirmed Noori had been the subject of a voluntary mental health treatment plan.

Outlining plans for heightened police presence at events in Victoria - including the Boxing Day Ashes Test, Andrews described the incident as a “cowardly” and “evil” act that has “sickened and angered all of us”.

Police minister Lisa Neville has said police had so far found no evidence at Noori’s home to suggest he had been radicalised, however, the homicide squad and counterterrorism command are both investigating.

Three people, including two South Korean nationals, remain in a critical condition in hospital after a car ploughed into pedestrians on Flinders Street in Melbourne on Thursday.

The white SUV drove on to tram tracks and then into an intersection crowded with pedestrians about 4.45pm, injuring 18 people before hitting the concrete base of a tram stop.

The alleged driver of the car was arrested at the scene by an off-duty police officer.

The off-duty police officer underwent surgery on Friday and is one of 12 people remaining in hospital.

• This story was amended on 27 December 2017 to comply with a suppression order.