Firebrand preacher Sheikh Ustadh Mohammed Junaid Thorne made the explosive claims on Facebook as he paid tribute to the slain Endeavour Hills teenager.

Haider, 18, had an Islamic flag with him when he was shot dead after stabbing two counter-terrorism police officers.

“We understand that the local authorities had cancelled the passport of this young boy for no reason, keeping him a captive in his own country for no valid purpose,” Sheikh Thorne wrote.

“We also understand that the police visited or raided his house (not clear yet) as he was hanging out with some friends in Hungry Jacks, just hours before his death.”

“The police then requested him (or forced him) to come in for a brief meeting or questioning.”

Sheikh Thorne said Haider’s friends tried to talk him out of visiting the police station, but he said he had nothing to hide or be afraid of.

“Unfortunately, our young brother went alone to meet with these “ambiguous” policemen, the violators of his privacy, and it is still unknown the details of what happened then,” he wrote. “What we are sure of though is that he was murdered in cold blood right in front of a police station, in front of a place that is supposed to be providing security and comfort to our youth.”

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Haider, whose recent behaviour had caused authorities “significant concern”, had his passport cancelled about a week ago on security grounds.

Victoria Police Chief Commissioner Ken Lay said the Afghani teen, a past member of radical Islamic group Al-Furqan, first came in contact with police three months ago.

He said officers had previously spoken to Haider but his activities had heightened in recent weeks. ????

“We first became aware of this male three months ago when he came into contact with Victoria Police,” Mr Lay said.

“It’s true to say late last week we learned of some behaviours that were causing us significant concern and our interest was greatly heightened.” ???

A constant stream of wellwishers and family have visited Haider’s Endeavour Hills home today. While today it’s in mourning, last night it was crawling with counter-terror officers.

A relative who answered the door said the family were grieving.

The teen’s mother Suraya has barely spoken since the news was broken to her last night.

“She did not know what her son was doing,” the friend told the Herald Sun.

“She is in shock and very upset.”

The teen’s 20-year-old brother is comforting his parents, the friend said.

“We are in mourning, we have not buried the body we have not seen the body, “ he said.

A neighbour said the teenager had lived at his Endeavour Hills home for several years.

He said Haider would politely nod a greeting in the street.

Earlier it was confirmed that Haider had been waving a flag supporting terror group Islamic State at a shopping centre, bringing him under scrutiny.

It is understood it was at Dandenong Plaza Shopping Centre.

“It’s true to say some of our people came across this person in public places and held conversations with him,” Mr Lay said.

Australian Federal Police Acting Commissioner Andrew Colvin said the investigation was in its early stages but no specific threat had been made by Haider against Prime Minister Tony Abbott despite reports.

Mr Colvin said “a range of factors” heightened the police interest in the Muslim teen in recent days. ????

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Mr Colvin said a decision was made to talk to Haider about his “rhetoric” and his intentions.  ????

Counter-terrorism officers met Haider outside Endeavour Hills police station in Melbourne’s southeast about 7.45pm after the teen told police he felt uneasy about taking in the station’s foyer.

He greeted the officers with a handshake before stabbing an AFP agent in the neck, abdomen and upper body.

He then stabbed a Victoria Police officer twice in the arm.

Victoria Police Assistant Commissioner Luke Cornelius said the Victorian officer fired a single shot that killed Haider.

The AFP officer has undergone surgery in Melbourne and is in a serious but stable condition.

The Victoria Police officer will have surgery today and is in a stable condition.

Police said they had “no choice” but to shoot the teen dead after the stabbings.

“I think the fact that the Joint Counter Terrorism Taskforce was doing some work around him indicates our level of concern,” Mr Lay told 3AW radio today.

Mr Lay said Haider “had one thing on his mind and that was to do the most amount of harm to these people (police officers) that he could”.

Mr Abbott said the incident in Melbourne’s southeast shows some Australians are capable “of very extreme acts” and would do their countrymen harm.

“The suspect did mount a fierce attack on both officers,” Mr Abbott said in a statement issued from the US.

“Obviously, this indicates that there are people in our community who are capable of very extreme acts.

“It also indicates that the police will be constantly vigilant to protect us against people who would do us harm.”

Mr Abbott was briefed on the incident while travelling to New York to attend United Nations meetings dealing with the rising threat of the Islamic State.

Islamic Council of Victoria secretary Ghaith Krayem said members of Al Furqan told him Haider hadn’t been a part of the group for a while.

Harun Mehicevic, leader of Al-Furqan in Springvale, refused to confirm Haider’s alleged involvement in the group.

He said he would not comment on Haider’s attack on two police officers or discuss his death last night.

Speaking outside a Springvale flat near the Al-Furqan bookshop, the controversial sheik said the group was working on a statement to be released later today.

Al Furqan Information Centre in Springvale South was raided by counter-terrorism squads in 2012.

Horat Ali Batoor, a photographer representing Melbourne’s Afghani Hazara community, said Haider appeared to be of Aryan descent.

He said that Haider was not linked to the Hazara community who moved to Melbourne in the 1990s.

“He’s Aryan looking,” he said.

“Probably he was born here.”

Mr Batoor condemned the attack.

“We totally condemn this action,” he said.

“Terrorism is not acceptable, we came here to escape terrorism.”

A large crime scene remains in place at the police station as detectives continue to investigate.

Police and SES members erected a tarp and makeshift wire fence around a silver sedan, believed to be Haider’s car. Detectives removed what is believed to be evidence in paper bags from the scene.

“Our members had no inkling that this individual posed a threat to them,” Mr Cornelius said.

“It’s absolutely clear to us that our members really had no choice other than to act in the way in which they did.”

Mr Lay said the officers would get help to recover from the physical and mental trauma of the attack.

“These were two young men who turned up to work, doing their job, keeping their community safe, in a very very difficult environment,” he said.

Mr Lay has written to all Victoria Police members today warning them to be alert and prepared for any situation.

There will be extra police at the AFL Grand final on Saturday, including undercover operatives.

Mr Cornelius said it was “important that the community understands this is not an exercise in police seeking to single out particular individuals in the community”.

“Where we see individuals in the community behaving in a way which causes a concern to public safety, we have to reach out to those individuals and do what we can to understand what it is that they might be planning to do and put ourselves in a position to deal with those individuals in a way which is safe and in a way which promotes community safety,” he said.

The homicide squad will investigate on behalf of the State Coroner, with the police Professional Standard Commands to oversee the investigation.