Bosses of a new £10 million mental health unit have moved to reassure staff that plans to treat young and older people together will work.

Bradford District Care Trust, which manages mental health services and learning disability services in Bradford and Airedale, is currently in the process of building the new unit in the grounds of Airedale General Hospital, near Steeton.

The 60-bed unit will replace wards four, 11 and 12 in Airedale Hospital as well as the therapeutic centre. Ward 24, which treats people with dementia will remain within the main hospital site. It has recently undergone a total refurbishment.

The Trust, headed by chief executive Con Egan, said the unit would provide a needs-led, rather than an age-led service, with built-in flexibility so the facilities can adapt to changes in practice and needs.

But some staff have raised fears that elderly patients will have to mix with patients under 65 for the first time which they say could be dangerous for elderly patients given the particular problems of some of the younger patients - some of whom have drug problems.

Staff have told Trust bosses it could leave the elderly vulnerable and open to abuse. But a spokesman for the Trust said: "People will be treated appropriately, according to their condition and needs, rather than age, in line with the Trust's strategic goal.''

The spokesman said the Trust was aware the issue of mixed age wards had been raised by a member of staff and said the concern was being dealt with to ensure the unit provided the appropriate environment and level of care for all service users so they could benefit as a citizen, regardless of age.

The spokesman added staff were obliged to raise any incidents of drug use on the wards so they could be dealt with appropriately.

"As with any section of the general population, there have been occasional incidents of drug use among service users and these have been dealt with in accordance with very clear national guidelines," she said.

"We have not had any issues surrounding drug dealing."

The new unit, which is expected to be completed by the end of the year, will be made up of bed areas separated into male and female sections, therapy areas and a psychiatric intensive care unit.

The intensive care unit is a new service for the district and will allow patients currently being treated out of the area to be cared for closer to home, their family and friends.

The single-storey building will include a multi-faith room, family room and courtyard area as well as outdoor spaces, natural lighting and modern design and layout.