Protesters were outraged at the revelation that a mobile phone firm has had an antenna on top of an Oxford maternity unit for 14 years.

The existence of the antennas at the John Radcliffe Hospital women's centre was only brought to light after Orange approached NHS managers with proposals to add a 3G network link.

Although the Oxford Radcliffe Hospitals NHS Trust, which oversees the JR, turned down the request, it has admitted the phone company has had an aerial on top of the seven-storey building in Headington since 1994.

It defended the siting but refused to say how much it is paid to allow the antenna.

About 5,500 babies are born at the women's centre and 700 newborns are treated at its special care baby unit every year.

Grandfather-of-eight Mick Haynes, 67, who has successfully fought against four antenna proposals in nearby Marston, was angry no-one was told about the aerial.

The 67-year-old retired scaffolder said: "I think this is terrible quite honestly. To put one on a hospital is ridiculous, but to have one on a maternity unit is insane.

"I should think new mothers will go mad about this. The hospital has gone behind everyone's back, because no-one around here knows anything about it.

"When I've done petitions I find young mothers are particularly concerned for their children.

"We're really concerned about the health risks.

"Experts aren't 100 per cent sure they're dangerous, but they're not 100 per cent sure they're safe either.

"You're not allowed to use a mobile inside hospitals and yet it's okay for them to have a mast on top."

John Willis, whose wife Rachel was treated at the John Radcliffe Hospital's maternity unit after their daughter Lucy was born in an A34 layby in June, believes people have the right to know where phone masts are sited.

The 36-year-old from Drayton, near Abingdon, said: "The whole problem is that nobody can give you accurate information about the health problems caused by masts.

"My personal opinion is that a maternity unit is not a good place for a mast, but I assume the JR managers would immediately take it off if evidence ever proved it was harmful."

Yasmin Skelt, of Mast Sanity, a UK organisation fighting against the insensitive siting of mobile masts, added: "The general population may not be at a very high risk from antennas, but pregnant women and babies need special care.

"It's mind-boggling that phone companies and hospitals can get away with this type of thing."

Orange said the radio base station at the JR, which has two satellite dishes and six antenna, provided "essential network coverage" for customers using its mobile service, and the lease had been negotiated with the ORH.

A JR spokesman said the mast was put up after a "careful review of Government policy and available evidence" and the agreement with Orange was kept under review.

She added: "There's agreed national and international safety guidance on mobile phone mast emissions, which we follow.

"We had the base station independently audited by the Radio Communications Agency (now OFCOM), which confirmed the level of emissions was well below the permitted levels. Patient safety, of course, remains of paramount importance and we'd review our position if new Government policy was produced, or new evidence became available."