Basketball: Vanessa Bryant sues helicopter company for deaths of NBA star Kobe Bryant, daughter

Vanessa Bryant has reportedly sued the helicopter company involved in the death of husband Kobe Bryant and daughter Gianna last month.

The NBA superstar and eight others - including pilot Ara Zobayan - were killed when their chopper crashed into the fog-covered Calabasas hills near Los Angeles.

Family, friends and fans have spent weeks mourning the tragedy, with thousands gathering for a memorial event at the Staples Centre on Tuesday (NZ time).

But the Los Angeles Times has revealed attorneys for Bryant's widow have filed a lawsuit against Island Express Helicopters and Island Express Holding Corp, claiming Zobayan "failed to use ordinary care in piloting the subject aircraft".

The suit says Bryant's death was "a direct result of the negligent conduct of Zobayan", with the company "vicariously liable in all respects".   

A preliminary National Transportation Safety Board investigation found no engine or mechanical failure.

According to the Times, Vanessa Bryant's lawsuit accuses Zobayan of several acts of negligence, including failing to abort the flight, failing to monitor and assess the weather, and failing to keep a safe distance between natural obstacles and the helicopter.

Zobayan, who was Bryant's regular pilot, was cited by the Federal Aviation Administration in 2015 for violating visual flight rules minimums.