WORK has begun to increase the capacity of the emergency and intensive care units at the Tweed Hospital as medical staff struggle to meet demand, operating at 100 per cent capacity for the past three weeks.

The holding works will act as a stop-gap measure to ensure the existing hospital is able to keep up with demand, while construction of the new $534 million greenfield Tweed Valley Hospital is underway.

Northern NSW Local Health District chief executive Wayne Jones said the current scope of work had begun in late 2017 with the arrival of a modular building at the rear of pathology, which is being transformed into an additional inpatient unit. This is scheduled for completion by mid-2018.

"These holding works are essential for us to be able to continue to meet the health care needs of the Tweed community while the new hospital is being built,” Mr Jones said.

"The community and our staff will benefit immensely from the new facilities, which will enable them to keep delivering the high standard, quality healthcare that they are known for.”

Mr Jones said the input of senior clinicians had been instrumental in determining the required scope of the holding works, which includes relocations, refurbishments, and expansion to a range of departments.

The works, due to be completed by early 2019, will see:

• The expansion of the emergency department;
• Additional clinical beds in the intensive care unit;
• An increased number of treatment chairs and consulting rooms for oncology;
• An additional CT machine; and
• Increased number of operating theatres and increased surgical recovery area.

Tweed Hospital Medical Staff Council co-chair Dr Mike Lindley-Jones welcomed the news, saying staff were struggling to cope with the current workload.

"The hospital is full and it has been for about three weeks - you can't get anyone in or out,” Dr Lindley-Jones said.

"It is just a sign of the fact that it is too small a hospital for the area. It really is difficult and it is going to be at least another five years before we get our new one - which we are very pleased about.

"Hopefully there will be enough beds and it will be able to operate a bit more freely.”

Dr Lindley-Jones said staff were concerned that bed projections for the new hospital had been "massively under-estimated”.

"A lot of the projections are based on the services we currently provide, but the service we currently provide is based on the fact we are currently at capacity,” he said.

"We can't grow it when we are at capacity and physically constrained.”

Currently, the Tweed and Murwillumbah hospitals offer a combined 300 beds.

Mr Jones said a location for the new hospital was expected to be announced soon, with final negotiations with landowners currently underway.

He said 20 sites had been identified through the public expression of interest (EOI) late last year, with an additional 11 sites not put forward in the EOI also reviewed to ensure all available options were considered.

Tweed MP Geoff Provest an announcement on the location of a new ambulance station at Pottsville was expected to be made in early April.