A real-life tractor beam that can invisibly ensnare and levitate objects has been developed by British scientists.

It uses a 3D "hologram" of high intensity sound rather than space-warping rays and is not quite up to the job of capturing a star ship.

But at the level of targets less than a millimetre across the device created by Bristol and Sussex university researchers performs just like its classic sci-fi counterpart.

Tiny objects can be lifted into the air, moved up-and-down or from side-to-side, and rotated simply by adjusting output of 64 miniature loudspeakers.

Possible applications include moving and assembling delicate electronic components or transporting drug capsules or micro-sized surgical instruments through living tissue.

Professor Sriram Subramanian, from the University of Sussex, co-founder of the sonic technology company Ultrahaptics, said: "In our device we manipulate objects in mid-air and seemingly defy gravity.

"Here we individually control dozens of loudspeakers to tell us an optimal solution to generate an acoustic hologram that can manipulate multiple objects in real-time without contact."

The tractor beam works by surrounding an object with high-pitched, high-intensity sound waves to trap it within an acoustic force field.

Different shaped force fields made of sound were found to function as tractor beams, the scientists reported in the journal Nature Communications.

One resembled a pair of fingers or tweezers, another took the form of a swirling "vortex", and a third enclosed the object in a "cage".

Phd student and lead author Asier Marzo, from the University of Bristol, said: "It was an incredible experience the first time we saw the object held in place by the tractor beam. All my hard work has paid off, it's brilliant."

Colleague Bruce Drinkwater, professor of ultrasonics at Bristol, added: "We all know that sound waves can have a physical effect. But here we have managed to control the sound to a degree never previously achieved."