The 48-year-old was shot in an apparent ambush outside his Altona North home, in Melbourne's inner-west suburbs, on Sunday evening.
Emergency services responded to reports he had been shot in a car in the driveway of a home shortly before 8pm, police said.
Haddara was taken to hospital with life-threatening injuries after the targeted attack.
He is alleged to be the head of his namesake family clan, linked to Melbourne's illicit tobacco trade.
The Haddara group has reportedly been a long-time rival to a syndicate led by tobacco kingpin Kazem Hamad.
The latter has been connected to a series of high-profile firebombings in Victoria while fighting for control of importation and distribution of illicit tobacco.
Hamad was arrested by Iraqi authorities following his deportation from Australia in 2023 and recently jailed for life.
Haddara last made headlines in 2025 when police withdrew a range of gun charges against him following an investigation into illicit tobacco and organised crime.
He faced an additional charge of affray by using unlawful violence over an incident in Altona North in November 2022, but it was withdrawn in March 2024.
In a statement issued through their lawyers, Haddara's family requested privacy as they "focus on the wellbeing of their loved one".
Officers from the Major Crime Scene Unit remained at the scene into Monday morning, where a stretch of Marigold Avenue was closed to traffic.
Police directed motorists away from the site of the shooting, which was cordoned off under a blanket of fog.
Haddara's brother Mohammed was killed in a shooting on Fifth Avenue in 2009, a short distance from the site of Sunday's shooting, after an argument about a Mercedes borrowed for his sister's wedding.
In 2019, Ali Chaouk was jailed for at least 18 years for the murder.
Ahmed Hablas, the cousin of Chaouk's wife, initially confessed to the killing but retracted his statement and was acquitted by a jury in 2011.
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