A NATIONAL investigation into NHS waiting times has been launched by Audit Scotland after a health board manipulated figures to avoid breaching Government targets.

The watchdog will examine whether boards are doctoring figures to wrongly log patients as unavailable for treatment.

The investigation follows revelations in October that NHS Lothian patients who refused to travel to England for treatment were removed from the 18-week list.

The board's chief executive, Professor James Barbour, quit his £195,000-a-year job last week.

Labour Party health spokeswoman Jackie Baillie, who pushed for the investigation, said: "This is a hugely positive development and comes in sharp contrast to Nicola Sturgeon's attempts at Holyrood to block an inquiry into the SNP's hidden waiting times scandal.

"Scottish Labour has been pressing the Government to hold a full, independent, Scotland-wide investigation for months now.

"But at every turn the SNP seemed desperate to brush our concerns under the carpet.

"Patients and the public deserve to have complete confidence and I am delighted that the Auditor General has instructed this inquiry.

"I will be writing to the Auditor General urging him to also examine the culture that has led to waiting times being manipulated to determine whether undue pressure was put on health board staff to fiddle waiting times by SNP ministers."

In a letter to Ms Baillie, Audit Scotland's director of performance audit, Barbara Hurst, said: "The Auditor General has now asked Audit Scotland to review the management of NHS waiting times, recognising the importance of this for patients and the public and the need for independent assurance in this area.

"We will examine how social unavailability codes have been used by NHS boards and will focus our attention around the period when discrepancies came to light in NHS Lothian."

The report will be presented to Parliament after the summer recess.

Ms Sturgeon ordered an investigation in March into NHS Lothian's management culture.

The move came after it emerged more than 1200 patients had been referred to English hospitals, but when they declined they were omitted from a list of patients waiting more than the target 18 weeks for treatment.

Two member of staff were suspended as part of the probe.

Ms Sturgeon has already asked NHS boards to review their waiting times practices with the help of Audit Scotland.

A Scottish Government spokeswoman said these internal reviews, alongside the wider Audit Scotland investigation, "aim to provide confirmation that waiting times practices are completely transparent right across the country".

Ms Sturgeon said: "There is no evidence these practices are widespread. However, it is important to show that recording of waiting times data is accurate and transparent.

"That is why I have asked all territorial health boards to undertake a specific and detailed audit of local waiting-times management and processes, as part of each board's internal audit programme over 2012-13."