Google has unveiled a prototype smartphone with "customised hardware and software" that enables it to create 3D maps of a user's surroundings.

The device's sensors allow it make over 250,000 3D measurements every second and update it's position in real-time.

Google said potential applications may include indoor mapping, helping the visually-impaired navigate unfamiliar indoor places unassisted and gaming.

It has offered 200 prototypes to developers keen to make apps for it.

Google said its Advanced Technology and Projects (ATAP) unit developed the phone as part of a project called Project Tango with help from researchers at various institutions.

"We are physical beings that live in a 3D world. Yet, our mobile devices assume that physical world ends at the boundaries of the screen," the firm said.

"The goal of Project Tango is to give mobile devices a human-scale understanding of space and motion.

"We're ready to put early prototypes into the hands of developers that can imagine the possibilities and help bring those ideas into reality," it added.