Using a mobile phone inside a hospital may risk the lives of patients by interfering with equipment, according to academics.

Signals from mobile devices may alter the performance of pacemakers and other life-saving machinery, says the study from the University of Amsterdam.

Researchers recorded 50 incidents of electromagnetic interference caused by mobile use, and classified 75 per cent of them as being hazardous.

Most of the problems result from General Packet Radio Service signals, a data transfer service used by the most recent handsets.

Mobile phones should be kept at least a meter away from hospital beds and equipment, according to advice published in online medical journal Critical Care.

'Critical care equipment is vulnerable to electromagnetic interference by new-generation wireless telecommunication technologies with median distances of about three centimetres,' says the report.