A Northern Ireland health trust is being charged up to £100,000 a year for some of its agency nurses to address acute shortages of permanent staff, it can be disclosed.
The cost of an uncontracted agency nurse in the Northern Health Trust can be up to four times more than that of a staff nurse, the Press Association has learned.
In some cases agency nurses are costing more than a consultant's salary.
The trust is being forced to pay the large sums because of a chronic shortage of trained nurses.
The situation has been described by an MLA as "privatisation by the back door".
Head of the Northern Trust, Dr Tony Stevens, disclosed the pay during a meeting with SDLP MLAs Patsy McGlone and John Dallat.
Dr Stevens told the politicians a band five agency nurse can cost the trust up to £100,000 a year - up to four times that of a staff nurse of similar grade.
The average wage of a staff Band five nurse is £21,000 to £28,000 per annum.
He also said that in some cases agency nurses are costing more than staff consultants, who are paid between £76,000 and £102,500 a year.
In addition, an agency consultant can cost the trust up to £300,000 a year.
The Northern Trust said a failure to recruit enough nurses and doctors has led to an increasing use of high-cost non-contract agency staff.
The trust warned it is a situation it cannot afford.
In a statement to the Press Association it said: "There are regional and national nursing shortages, and we are actively trying to recruit permanent nursing staff locally, nationally and internationally.
"Failure to recruit the numbers of nurses and doctors that we need means having to resort to increasing use of high-cost non-contract agency staff which can be three to four times the cost of equivalent trust-employed staff.
"That is a position that we simply cannot afford."
Mr McGlone said action was urgently needed to curtail the spiralling costs.
"Because of a lack of nurses we have a situation which seems to be privatisation through the back door.
"This unregulated pay spiral is going out of control and leading to this crazy situation," said Mr McGlone.
He added: "We need to stop this by training nurses and medical staff and paying them properly to reflect the important role they play.
"We must stop this privatisation by the back door."
It is understood that it could take up to five years to train enough nurses to meet demand.
All Health Trusts have been ordered to make £70m budget cuts. A reduction in agency staff is one of a number of proposals to help deliver the savings.