A council in Cornwall is demanding the removal of a new police radio mast.
The Tetra system means police cannot be overheard
The mast, at Treworval Farm in Mawnan Smith, was put up in November by 02 without planning permission.
An application for retrospective planning permission was refused in March and Kerrier District Council said the Tetra mast had to be removed.
On Friday the council confirmed legal papers for an enforcement notice were being prepared. O2 said the mast had been erected under "emergency powers".
A company spokesperson said it had needed to complete a chain of "transceivers" for the system, which cost nearly £3bn.
It said the company was in negotiations with the landowner and the council.
There are 200 Tetra police masts in the South West, which allow police officers to communicate over secure radio links.
The masts have prompted protests from some people at several sites in Devon and Cornwall who claim there has not been enough research into possible health risks.