The group of residents tried unsuccessfully to stop O2 putting up the mast in the West Sussex village of Rogate on Saturday at 0200 GMT.

Now they are holding a vigil to block access to the mast in an attempt to stop it being turned on.

They believe the technology used in the mast, designed to boost emergency services' radio coverage, can cause cancer.

The local parish council are livid because this mast has been turned down for planning permission but it has been put up with total disregard for all democratic processes Norman Coleshill, resident

Another phone mast was also put up during the weekend at Bowhill Farm, east Marden, near Chichester, before planning permission had been issued, according to Chichester District Council.

Chichester District Council has said it is considering issuing an injunction to stop both masts being used until planning permission is granted and may also issue an order for them to be removed.

Resident Norman Coleshill, 63, a retired finance worker for IBM, said: "The local populace, particularly those with kids, feel that there is a risk of cancer.

'Exceptional measure'

"There are many scientists who feel there is a danger of cancer from long-term exposure.

"The local parish council are livid because this mast has been turned down for planning permission but it has been put up with total disregard for all democratic processes."

Susan Moore, spokeswoman for 02 Airwave, said the masts had been put up before planning permission had been granted to meet the company's deadlines.

She said: "Whilst we regret the need to proceed in this way, we would emphasise that this is an exceptional measure that has not been taken lightly, and that any site that is to become a permanent part of the Airwave network must achieve planning approval."