CONTROVERSIAL Tetra masts have been given the go-ahead by council chiefs despite concerns from union leaders.

Tetra communications are already used by the police and ambulance services and Dorset Fire and Rescue Service hopes to introduce the system to replace its existing VHF radios and needs the antennas to get the scheme off the ground.

It proposed to install two masts on the fire and rescue services HQ next to County Hall and one on the emergency headquarters in Dorchester Library.

Members of Dorset County Council approved their installation despite concerns raised by local government union Unison, after hearing the antennas would be removed when the fire control room is relocated to the regional control room in 2010. Elaine Taylor, director of corporate services at the county council, told the meeting: "Unison is strongly opposed to any Tetra system within the County Hall site."

Council leader Angus Campbell said that although it made sense to have the system in place he was concerned about the effect it could have on people working nearby.

But he said it would be hard to evaluate the potential effects until the masts were in place.

"We have to be very sensitive to the potential fear from these things. It's quite difficult when we are looking at two issues - fear over health and safety and the fact that it is needed - to make a decision."

Councillor Hilary Cox said that the cabinet should follow advice from the Government that the Tetra masts are safe and erect them.

Members of the committee agreed that they should be installed but monitoring of radiation levels emitted from the masts, which has been the main concern, should start straight away to reassure staff that they are safe.

Similar antennas disguised as flagpoles were recently given the green light for the Keep military museum to be used by the police.