For the first time, California residents can legally receive deliveries from a driverless vehicle delivery service.

According to the BBC, a robotics start-up called 'Nuro' expects to launch its driverless delivery service in the state by 2021.

In April, California became Nuro's testing ground for its R2 vehicles, but now that the company has legal approval for its delivery service it can begin charging customers a fee.

The start-up's driverless vehicles cannot drive faster than 35 mph, and will only be allowed to take to the roads in "fair weather" conditions.

“Issuing the first deployment permit is a significant milestone in the evolution of autonomous vehicles in California,” said California Department of Motor Vehicles director Steve Gordon.

“We will continue to keep the safety of the motoring public in mind as this technology develops.”

Nuro was founded by two former Google engineers and has funding from Japanese firm Softbank, the BBC notes.

Its R2 is an egg-shaped autonomous vehicle that moves about with the assistance of radar, thermal imaging and 360-degree cameras. The car has neither a steering wheel, pedals nor side-view mirrors.

The R2 also features  two temperature-controlled compartments for deliveries. Doors raise up to reveal the items once a code has been entered by the recipient.

Despite the bells and whistles, one transport expert said safety issues is still a concern.

"It will be very limited to begin with while the technology is thoroughly evaluated," said Prof David Bailey from the University of Birmingham.

"So, for example, the vehicles will only be allowed on 'surface streets' with their speed limited to 35mph, and the smaller Nuro delivery bots will be limited to just 25mph.

"It's essentially a limited trial, but still a significant step towards a driverless future."

In October, driverless taxis began operating in Phoenix, Arizona, as part of Google's Waymo service.

According to the BBC, a similar service, backed by the online tech and retail giant Alibaba, is currently being tested in  Shanghai, China. 

A number of other driverless vehicle trials are being conducted across the world.