Several Welsh health trusts have merged during the year
The NHS in Wales is facing potential clinical negligence claims of up to £500m, it has been disclosed.
There has been concern for many years about the spiralling cost of clinical negligence claims and trusts expect to pay out more than £140m this year.
Opposition parties have voiced concerns about the potential scale of compensation, set in the NHS accounts.
But the assembly government said it had to include projected figures which were not necessarily the amounts paid out.
Future liabilities are potentially several times the £140m figure although many cases are currently in dispute.
The accounts also show that performance against key risk management targets including patient safety and clinical governance declined last year.
These are directly linked to the challenge of merging several trusts during the year.
The accounts point to a "challenging operating environment" caused by the restructuring as a reason why the performance fell compared to the year before.
The targets cover risk management in the areas of health and safety of patients, staff and the public, learning from incidents, and clinical governance.
Opposition parties say they are worried that the same could happen following the major restructuring of the NHS currently underway as well as voicing deep concern about the potential scale of the compensation bill for clinical negligence.
Welsh Conservative health spokesman Andrew RT Davies said: "These accounts lay bare the state of the NHS in Wales today. Reorganisation after reorganisation has hit patient care just as we said it would, millions are being paid out because of negligence, admin and agency costs are rising.
"The health minister said last November that she was trying to minimise any risk of service disruption resulting from NHS restructuring. This report suggests those efforts have failed and that patients have suffered as a consequence.
Standards of learning
"What patients and NHS staff need now most of all is a period of stability, where doctors and nurses are in control of the day-to-day running of the health service locally, not government ministers in Cardiff."
Liberal Democrat health spokesman Peter Black said: "It's very worrying that the standards of health and safety of patients and staff and the standards of learning from incidents within the trusts declined within the merged NHS trusts last year.
"This demonstrates what we said at the beginning of this restructuring process that any change in the NHS will have an impact on service and patient care and this has to be taken into account when the minister rearranges the NHS.
"With the changes in the LHB about to come into force, there must be guarantees from the minister that this won't happen again."
Health economist Prof Marcus Longley, of the University of Glamorgan, said: "It is a lot of money, clearly. The average medium-sized hospital costs in the region of £200m a year to run, so this is the cost of one hospital basically.
"In those terms, this is a lot of health care being spent because the NHS has made mistakes."
However, a Welsh Assembly Government spokesperson said it was inaccurate to suggest that clinical negligence payments were rising.
"We are obliged under accountancy rules to include a projected figure in the accounts. The projected figures are not necessarily the amounts that are actually paid out. Payments vary year-on-year and depend on the type of cases that may be in the system.
"The health minister has made it clear that high standards on risk management are maintained during, and after, the period of change in the NHS.
"Robust transitional arrangements have been put in place to support organisations in maintaining their focus on safe, high quality patient care."