The long-delayed new maternity unit at Belfast's Royal Victoria Hospital could be built five years ahead of schedule, the health minister has announced.

Michael McGimpsey wants to examine whether it could be housed in the top three floors of the critical care building that is currently under construction at the RVH site, rather than building a standalone women's facility.

The move, if approved, would save an estimated £100m. Budget constraints had seen the department put back the projected build date for the women's hospital to 2017/18.

But under the alternative plan, a state-of-the-art maternity unit could be opened at the RVH in 2012/13. It is one of a number of options that the Belfast Trust will examine in a review of the usage of the critical care building.

"Given the current challenging economic climate facing the Health and Social Care service in Northern Ireland, it is vital that any funds are invested in areas of greatest need," Mr McGimpsey said.

"The new critical care building is a much-needed development and I want to assure the public that work will continue to complete it.

"However, I also want to ensure that we maximise the potential of this new facility. That is why I have asked for an urgent review which will focus on the best use of the top three floors of the building."

The review by the Belfast Health and Social Care Trust is due to be completed by the autumn.