Designs are being drawn up for a £90-million new ward at the Bristol Royal Infirmary so that patients will no longer have to be cared for in the original 275- year-old building.

Detailed plans can now be made to move all hospital services out of the Old Building in Upper Maudlin Street after managers approved the project.

It will see the 18th century structure being replaced with a purpose-built seven-story building behind the BRI, which will also incorporate children's services and staff and visitor restaurants.

The project could see the BRI Old Building and Bristol General Hospital sold to help raise funds for the construction of the new block.

The sites have been declared surplus to the hospital's requirements, but members of the board have asked for a review of possible options for the BRI site before they agree to its sale.

Planners at the hospital have been working on this project since 2000 so that they can move away from the old Nightingale wards in the Old Building and the King Edward part of the BRI complex into a new building.

Most patients moved out of the Old Building when the Bristol Heart Institute opened in May.

Extra space also needs to be made available to complete the centralisation of children's services at the Bristol Children's Hospital, which was a recommendation of the Kennedy report in the wake of the heart babies scandal.

Plans will now be drawn up for a planning application to be submitted to Bristol City Council in April.

Work on the site will start with the demolition of a former nurses' home in Terrell Street to make way for the new ward block. The seven-story block will accommodate 160 adult patients on five floors, along with the rheumatology clinic that will move from the Old Building, and a floor for children's services. There will also be two floors for staff and visitor dining facilities and clinical offices.

Radiology services and operating theatres in the King Edward Building in the main BRI complex will remain when inpatient wards move into the proposed new block, with administrative services and other non-clinical departments likely to move into the space that creates.

Director of corporate development at University Hospitals Bristol Robert Woolley said the trust was likely to apply for a loan of up to £60m to pay for the project.

Financial director Paul Mapson said savings would need to be made across the trust to enable the project to go ahead.

The chairman of UHBristol's trust board, John Savage, said that the redevelopment in the city centre would support the plans for the superhospital at Southmead.

UHBristol chief executive Graham Rich said: "I think it is fantastic to be in this position to make a decision after months and months and years and years."