NHS plans to extend a mental health unit in Dorset will be unveiled today.

The Dorset HealthCare Pebble Lodge unit in Alumhurst Road, Bournemouth, known to council planners as Herbert Hospital, is to be expanded as part of NHS Dorset's restructuring of mental health services.

A pre-application hearing will take place before the planning board, prior to a planning application being submitted.

Mike Kelly, Dorset HealthCare’s head of mental health, said: "NHS England has commissioned an additional two beds to be provided at Pebble Lodge on our Alumhurst Road site, increasing capacity from 10 to 12.

"Pebble Lodge is a child and adolescent mental health inpatient unit which was recently awarded ‘outstanding’ status by the Care Quality Commission and is nationally accredited by the Royal College of Psychiatrists.

"The extension will ensure more young people in Dorset can be treated locally in an inpatient setting, rather than have to travel out of county.

"As we develop a full planning application, we will talk to planners and our neighbours to help ensure the extension fits in with the local area."

Councillor David Kelsey, chairman of the planning board, said the plans could prove controversial with some neighbours.

"They have been granted some funding to increase the size of the facility there with extra bed spaces," he said.

"It could be quite controversial, it is in a conservation area, there are a lot of trees which could be removed, there could be an impact on local residents.

"So they want to come in and explain what they want to do."

Cllr Kesley said the board would consider the strategic importance of the plans as well as the impact on the site and residents.

Several buildings on the site are Grade II listed, and the main building is thought to have been based on designs by Florence Nightingale.

"This is at a very early stage," said Cllr Kelsey.

"We will have to look at whether the need outweighs any change in policy."

The board will hear the plans at the town hall at 2.30pm.