The Advertising Standards Authority has upheld a complaint against emergency medical charity Magpas about misleading advertising, made by fellow charity the East Anglian Air Ambulance.

The EAAA made a complaint to the ASA about two banner advertisements, displayed in various locations, including at an Asda store in Ipswich, in which Magpas made the claims 'saving lives day and night', 'your day-time air ambulance' and 'your night-time air ambulance service'.

The EAAA also challenged whether the following claims, made on the Magpas website, were misleading and could be substantiated: 'Magpas Helimedix – Saving lives... Anyone, anywhere, anytime!' and 'By helicopter we can get to virtually anywhere in the East of England within 30 minutes!'

Magpas, which is based in Cambridgeshire, said that when the advertisements appeared in February, it was able to use Cambridgeshire Police's helicopter to provide a night-time air ambulance service between 1am and 7am, and outside those times it used land vehicles to respond to emergencies.

It provided data to show it had attended incidents in the locations referred to on a map on its website.

However, the ASA upheld all three complaints, saying that the helicopter had only been available for 63.7pc of shifts between January and September in 2011, and that other data provided did not substantiate its claims that a member of the team could be with patients, in the vast majority of areas within the East of England, within 30 minutes.

The ASA said the advertisements must not appear again in their current form and it reminded Magpas to ensure it holds robust substantiation to support claims in future.

Antonia Brickell, from Magpas, said: 'The ASA approached us and we take any communication of this kind very seriously.

'We have discussed and dealt with every issue raised. If there has been any misunderstanding then everything has been acted upon.

'Nothing has ever been done to ever intentionally mislead the public and we are proud of being a very open and honest charity.'

The Cambridgeshire Police helicopter was withdrawn from service in April and since then Magpas has leased its own helicopter, but this is limited to flying during the day.

It still continues to operate at night using land vehicles.