Two men walked into a shop with their faces partially obscured but the warning they delivered from a voice on the other end of a phone was crystal clear.

“Call Kaz or you will have no shop anymore,” the unknown voice on loud speaker told the shop attendant.

Just weeks earlier, a different man had walked in and handed over a piece of paper with a phone number, asked if the shop owner knew “Kaz” and demanded he give it a ring.

The two incidents from April and May 2024 were captured on CCTV at a shop in Hume in Melbourne’s north.

They are being probed by detectives investigating a long-running conflict between rival organised crime syndicates over illegal tobacco in Victoria, including more than 100 firebombings.

Detective Inspector Graham Banks said the incidents in the footage amounted to “extortions” and the shop owner was so concerned about what happened he sold up and changed his address.

Banks revealed who Victoria Police believe “Kaz” is, as he declared the investigation into the tobacco conflict had finally reached a significant turning point.

“We believe that person to be Kazem Hamad, who obviously controls this syndicate,” he said on Thursday.

Victorian courts have previously been told Hamad is allegedly running the his family’s organised crime operations from the Middle East.

Banks said syndicate members and the public were increasingly cooperating with police, pointing to the arrest of five people earlier on Thursday over an alleged $100,000 extortion and arson.

“We are getting cooperation from a number of people, including people aligned to Kaz Hamad,” he said.

“The scale and number of arrests we’ve been making recent times … indicate that we’re having that sort of assistance.”

He urged people who recognised any of the three men in the 2024 footage to come forward. But he said the people seen on CCTV were usually “far enough removed” from top syndicate members.

The incident involving a man who handed over the number happened on the afternoon of April 28, 2024. Police describe him as Pacific Islander in appearance, about 175 centimetres tall and of medium build.

The episode involving the men who delivered the anonymous message over the phone happened on the night of May 14, 2024.

They are both described as African in appearance, about 185 centimetres tall and of a slim build.

Banks said they were all on the “cusp” of being underage but looked to be aged about 20.

Demands from syndicates to shop owners are believed to be up to $5000 a month. That has sparked a plea for any owners approached to pay money or who are otherwise threatened to come forward immediately.

Banks said shop owners selling illegal tobacco were technically doing the wrong thing but the product was otherwise legal so he had sympathy for them. He said their offending was not equivalent to syndicate crimes.

“There’s a blatantness to this offending, I think historically it’s been allowed to go unchecked and hasn’t been reported,” he said.

-AAP