An Italian crime boss was given a lavish sent-off, with a helicopter dropping rose petals as a gilded, horse-drawn funeral carriage travelled through central Rome while music from The Godfather soundtrack was played, to the outrage of the local population.

Banners hailing Vittorio Casamonica as the King of Rome, picturing the 65-year-old leader of the Casamonica clan operating in the south-west of the capital near the Colosseum and St Peter's Basilica, were erected outside San Giovanni Bosco church where hundreds of mourners gathered to pay their respects. "You conquered Rome, now you'll conquer paradise," another a banner read.

The funeral, which also featured a Rolls-Royce as a hearse and a brass band playing the theme from Stanley Kubrick's masterpiece 2001: A Space Odyssey, set off a political storm in the lethargic Italian mid-August, when the country shuts down for holidays.

Mayor Ignazio Marino twitted from his vacation in the US to say he had called Rome's prefect Franco Gabrielli demanding an explanation for how such an extravagant display was allowed, saying it was "intolerable that funerals are used by the living to send Mafia messages".

Gabrielli received a call also from interior minister Angelino Alfano who demanded a detailed report on the incident. The prefect replied to Italian media that authorities had not been notified about the service taking place.

The president of the parliamentary antimafia commission, Rosy Bindi said it was "alarming" that this display of Mafia power came as an investigation into crime syndicates infiltrating Rome is rocking the capital and its public administration, describing it as "unacceptable".

Despite the lavish funeral, police said Casamonica, the old leader of the namesake crime syndicate, was "on the margins" of organized crime and was not directly involved in the probe dubbed Mafia Capitale.

The Catholic Church was also engulfed in controversy. Many were particularly angered at the San Giovanni Bosco church, for it allowed the ceremony while a few years back it refused a funeral for a leading right-to-die campaigner, Piergiorgio Welby.

In 2006 it was the Archdiocese of Rome that ordered the church not to celebrate service for Welby, who had had accepted his wish to be taken off life support, suffering from muscular dystrophy. Writer Roberto Saviano tweeted: "The Church that denied funerals to Piergiorgio Welby yesterday granted them in grand style to boss Vittorio Casamonica".

The Vicariate defended its actions saying the two cases were different as Welby had repeatedly expressed his wish to go against Catholic teachings, while Casamonica might have repented on his deathbed, Il Corriere della Sera reported.

The parish priest, the Rev Giancarlo Manieri, described Casamonica's mourners as "old fashion Catholics", claiming he had no control over what happened outside his church, referring to the Hollywood-style parade, adding that funerals inside went on as usual. Manieri also said it would hold the funeral again as that is his job. "The member of a clan is nevertheless within the church," he told Il Corriere.