In an interview with the Belfast Telegraph, Michael McGimpsey warned that it will take "significantly more" than the £3.6bn pot of cash he has to bring hospital and health centre buildings and equipment up to a modern level of need over ten years.

He said the Health Service is facing an "enormous task" to modernise a number of hospitals across Northern Ireland, some of which are in such a bad state they need to be "knocked down and rebuilt".

The minister said he is now intending to focus on the capital funding needed to modernise hospital buildings through both short term and longer term plans.

"Our capital is seriously deplete," he said. "We need a major investment. There has been a stark underinvestment in the Health Service in terms of capital over the past 30 years and we've a number of hospitals that basically should have been replaced a long time ago and are not fit to be refurbished. Some of them actually need knocked down and rebuilt."

When asked if there was an estimate figure of how much extra investment would be needed, the minister replied: "We have a rough figure and I'm scared to tell you."

He highlighted Daisy Hill in Newry, Altnagelvin in Londonderry and Craigavon Area Hospital as examples of buildings that have not been invested in properly over the years.

"If you think back historically, these hospitals were built together, within a few years of each other, and instead of incrementally replacing them, they've all just been left and now we're faced with this enormous task of reinvesting," he said.

Mr McGimpsey said that in recent budget allocations, he managed to secure £3.6bn capital over the next 10 years, £700m of which will be made over the next three years on a variety of projects.

Looking to the longer term, however, the minister said he faces "great challenges in modernising the rest of the system".

"The Investment Strategy for Northern Ireland has allocated £3.6bn to health over the next 10 years. The fact is we need considerably more if we are to deliver the sort of change that is needed in ten years.

"In light of these constraints on capital funding, I will obviously need to carefully consider longer term investment proposals in terms of priorities, when determining final allocations of capital investment funds beyond the current budget period."

He outlined a wide range of projects that will be completed in the next three years.

"This includes the new £60m Downe Hospital, the first £100m phase of the Ulster Hospital, £100m for Phase 2B at the Royal Victoria, new health and care centres, costing £53m in total, such as Castlereagh, Portadown, and very important new mental health facilities costing £23m in Londonderry and Craigavon.

"This will be in addition to a new £15m Regional Adolescent Psychiatric Unit and Children's Unit in Belfast," the Minister said.

"Much more investment in ambulance and fire services, new technology and smaller investments in healthcare facilities will also be delivered in this programme. This will transform our health and social care services in the coming years, making them more effective, accessible and responsive."

Mr McGimpsey said he was pressing on with the procurement of investment for a new acute hospital planned for Enniskillen and a new local hospital for Omagh.

"This will bring over £450m investment in the west in 2012 and 2013. In addition we need to ensure further investment in our hospitals infrastructure including investments at the Ulster, and Royal and other acute and local hospitals," he added. "I am currently giving active consideration to all medium to longer term strategic investment proposals, including the Women's and Children's Hospitals."