Two Scottish health boards are facing "prolonged and considerable" financial challenges, public spending watchdogs have warned.

NHS Tayside needs to make savings of £175 million over the next five years while the NHS 24 advice service has seen the bill for its delayed new IT system soar by almost 75%, according to new reports.

Auditor General Caroline Gardner said the difficulties faced by the two boards would "continue to have an impact on the way they operate and deliver services".

She spoke out after the reports were published, detailing the issues NHS Tayside and NHS 24 are facing - which prompted claims from Labour that Health Secretary Shona Robison is "mismanaging our NHS".

NHS Tayside has received loans cash totalling £24.3 million from the Scottish Government over the last four years, according to a report by the Auditor General for Scotland.

The potential budget deficit for 2016-17 stands at £11.65 million but NHS chiefs have to make "unprecedented" savings of £58.4 million this year.

Over the next five years, savings of £175 million will need to be made, according to the report, while NHS Tayside will also have to repay £20 million of loan cash - known as brokerage - to the Scottish Government.

The Auditor General said the health board "does not have plans in place that fully address" this year's budget shortfall and added: "There is a significant risk that NHS Tayside will need brokerage again to break even."

While NHS 24 has invested heavily in a new IT system over the past six years, delays in implementing this have "led to additional costs and risks to NHS 24's ability to meet its financial targets in future years", according to the Auditor General.

The advice service received government loans of £20.756 million between 2012-13 and 2014-15, and has to date only repaid £400,000 of this.

The Auditor General's report said previous failures to launch the new system successfully, combined with "double running costs" of keeping the existing system operational, "meant that NHS 24 now estimates that total projected cost of the programme will be £131.2 million, 73% above the £75.8 million included in the original business case".

Ms Gardner said: "While action is under way to try and address these issues, there's no quick fix available and recovery will take time.

"It's important that the Scottish Parliament and the Scottish Government closely monitor progress to ensure circumstances do not worsen, to the detriment of staff and service users."

Labour health spokesman Anas Sarwar demanded Ms Robison "address the huge cuts to come in Tayside".

He said: "The SNP health minister has spent all summer denying that our NHS faces cuts, denying that staff are under pressure and claiming our NHS has enough resources, only to have her claims blown out of the water by her own health board."

He went on to state that "something has clearly gone badly wrong with the NHS 24 IT system - it is years late and millions over budget".

Mr Sarwar added: "Shona Robison's in-tray is overflowing with problems with our health service - she is mismanaging our NHS."

Conservative health spokesman Donald Cameron said: "The struggles endured by NHS Tayside and NHS 24 both point to a similar problem - the fact the SNP has done a dreadful job running the health service.

"This report details tens of millions of pounds that have been poured down the drain. That's cash which could have been spent on staff, repairing crumbling hospitals or funding vital drugs.

"Auditors have been extremely critical of the financial waste here and the Scottish Government needs to provide not only an explanation of how this has happened, but practical solutions for the future."

Green MSP Alison Johnstone said: "Today's report from the Auditor General is yet another warning to the Scottish Government to improve oversight of new IT systems.

"In recent months we've seen foul-ups in the farming payment system and the scrapping of a Police Scotland system.

"It's deeply concerning that something as important as an out-of-hours health advice service is so incredibly late and astonishingly over-budget."

Liberal Democrat health spokesman Alex Cole-Hamilton said: "In financial terms, NHS Tayside seems to be in intensive care.

"Ministers must work with the board to give management the support they need to turn things round while protecting vital services.

"NHS 24's new computer system has been plagued with difficulties from the outset. We are now tens of millions of pounds over budget and are yet to see a functioning IT package that delivers what was promised.

"The massive cost overruns from another SNP IT fiasco will have long-term implications for funding."

Ms Robison insisted the Scottish Government took the issues "very seriously".

The Health Secretary said: "We welcome the additional level of oversight and scrutiny, in addition to our own, and continue to work with the health boards concerned to address the issues raised.

"Patient safety is our top priority and at no point has this been compromised."

Ministers are "working closely" with NHS 24 to bring the IT system "back on track," she added.

"NHS 24 has fully acknowledged there were weaknesses in the past and has worked hard to strengthen the programme's governance arrangements.

"We are pleased to see that the first phase of the new system was successfully implemented last week with the introduction of a new telephone solution for six planned care services including Breathing Space.

"Further phases will bring the full system online, with national roll-out by the end of 2017. This new system will deliver a much improved service for patients."

Regarding NHS Tayside, Ms Robison welcomed steps the board is taking towards "putting in place a long-term plan to return to sustainable financial balance".

She said: "The Scottish Government will continue to work closely with the board to monitor their progress as they work to strengthen their financial position.

"This Government has protected and increased the NHS Tayside resource budget, by £182.1 million (35.2%) since 2006/7.

"This year alone, NHS Tayside's frontline budget has been increased by 5.8% to a total of £699.1 million."

NHS Tayside chief executive Lesley McLay said: "NHS Tayside, like many other public sector organisations, is facing a number of challenges over the coming years.

"The financial challenge is extremely important but there are other key issues which we must address to ensure our health services continue to be safe and sustainable and respond to the needs of our communities.

"I would like to reassure people in Tayside that delivering person-centred and safe health services is our priority."

While Ms McLay said the report "sets out some of the challenges which we experienced in 2015/16", she added the health board has "already taken decisive actions to address these to ensure NHS Tayside returns to sustainable financial balance in the coming years".

She stated: "Over the past 18 months we have been building a five-year transformation programme for Tayside to drive forward redesign and change.

"This is led by our clinical staff and the programme is now well under way. However, it is important that we are realistic about the timescales involved in this transformation."

NHS 24 chief executive Angiolina Foster said: "Delays in this major IT programme have led to a significant increase in costs and a review of how the organisation operates to fully understand why we were unable to implement the new system.

"Following a detailed review of the 2015 attempt to go live, we are planning a phased approach to the delivery.

"We are pleased to report that last week we successfully went live on the first phase of the revised programme with six planned care services now up and running on the new telephony system.

"The next stage is partnering with one health board to ensure all aspects of implementation are secure, prior to a broader national roll-out during 2017.

"We look forward to fully implementing the new system in 2017, which will not only enable NHS 24 to continue to deliver improved patient-centred services during the out-of-hours period, but will allow for the development of new ways of offering health and care to people across Scotland well into the future."