Medical scientists have developed tiny cameras that can be swallowed by a patient and steered around the body to deliver images of the oesophagus.

The first-ever control system for the "camera pill" is a joint development by manufacturer Given Imaging, the Israelite Hospital in Hamburg, Royal Imperial College in London and the Fraunhofer Institute for Biomedical Engineering (IBMT).

"In future, doctors will be able to stop the camera in the oesophagus, move it up and down and turn it, and thus adjust the angle of the camera as required, " said IBMT team leader Dr Frank Volke.

"This allows them to make a precise examination of the junction between the oesophagus and the stomach.

"If the cardiac sphincter is not functioning properly, gastric acid comes up the oesophagus and causes heartburn.

"In the long term, this may even cause cancer of the oesophagus. Now, with the camera, we can even scan the stomach walls."

Dr Volke explained that the team developed a magnetic device roughly the size of a bar of chocolate which the doctor can hold in his hand during the examination and move up and down the patient's body.

The steerable camera pill consists of a camera, a transmitter that sends the images to the receiver, a battery and several cold-light diodes which briefly flare up like a torch every time a picture is taken.

One prototype of the camera pill has already passed its first practical test in the human body.

The researchers demonstrated that the camera can be kept in the oesophagus for about 10 minutes even if the patient is sitting upright.