Masked bikers shot dead an Italian entrepreneur and his girlfriend at close range in a busy central Milan street, a mafia-style execution unusual in Italy's financial capital.

Organised crime in Italy has long been associated with Sicily, Naples, Calabria and other poorer regions in the south.

But over the past few years the tentacles of the mafia have reached Italy's prosperous north, where a Calabria-based organisation known as 'Ndrangheta has become active.

Massimiliano Spelta, a 43-year-old former owner of a pharmaceutical company, was approached by two men on a scooter shortly before 8 p.m. (1800 GMT) on Monday and shot with five bullets as he walked down Muratori street in central Milan, an Italian police official said.

His 21-year-old Dominican partner was gunned down as she attempted to escape holding her 18-month-old daughter, the only one to survive the attack. Both the killer and the driver of the scooter wore helmets that covered their faces.

The motive for the shooting was not immediately known, the police official said.