Police say terrorist suspect Numan Haider may not have acted alone, while Prime Minister Tony Abbott has rejected reports he was the target of threats.

Melbourne terrorist suspect Numan Haider may not have acted alone when he stabbed two counter-terrorism taskforce officers, before being fatally shot.

But Victoria Police Chief Commissioner Ken Lay has dismissed speculation the 18-year-old intended to behead the officers with a knife and wrap them in an Islamic State flag.

“There is nothing, absolutely nothing, that I’m aware of that would suggest that was the intention,” he told ABC radio on Thursday.

Police say counter-terrorism officers had been aware of Haider for about three months and were concerned about his behaviour and escalating rhetoric.

Officers went to Haider’s house in Narre Warren on Tuesday to set up an appointment and Mr Lay said it was unclear whether this had angered the teenager.

Controversial Muslim preacher Junaid Thorne said in a Facebook post Haider was angered by the visit.

“According to his friends, he received a call from his parents informing him that the police had been in the house and searched his room,” he wrote.

“Upon hearing this, the young boy got mad and called up the local police station, questioning why his privacy had been violated … and this lead (sic) to an argument with them on the phone.”

On Tuesday night, Haider was talking to others at the time or just before he attacked the Australian Federal Police and Victoria Police officers and was shot outside the Endeavour Hills police station.

“There’s some information that he was certainly talking to other people around the time that he came to the police station. Face-to-face,” Mr Lay said.

“It’s just a little unclear to us at the moment whether there was actually people at the police station with him, whether they dropped him off, whether they were waiting with him.” A second knife was found on Haider’s body.

Muslim cleric Sheikh Mohammed Omran, who visited the Haider family on Thursday, said they were devastated.

“I don’t think any one of us can tell you how the family feels – very devastated. When you lose your youngest son it’s not a simple thing, especially when you only have three sons,” he told reporters.

The al-Furqan Islamic Information Centre, which had past links to Haider, said it had no involvement in the incident.

“We would hope in these troubled time that we refrain from sensationalist assumptions and rely on the presumption of innocence,” it said in a statement.

Islamic Council of Victoria secretary Ghaith Krayem said on Wednesday that while Haider had been involved with al-Furqan, a group raided by police in 2012, he had not had recent contact.

Meanwhile, Prime Minister Tony Abbott played down reports Haider made terrorist threats against him.

“I haven’t been officially briefed to that effect, so I’d rather not further comment on it,” he told reporters in New York, after addressing the United Nations Security Council on the threat of terrorism.

Dr Shakira Hussein, a lecturer on Islam and gender at Melbourne University, said governments and police should be careful not to label the incident a terrorist attack until all the facts were clear, saying it might make it seem more sinister in the eyes of many.

“For people who are looking to be important, and are looking to be part of something big, that makes it more appealing rather than less,” she said.