Former Health Secretary Nicola Sturgeon must explain to Holyrood what she knew about the NHS waiting times scandal before it was exposed, according to Labour.
The party will bring forward a debate on the issues surrounding waiting times at the Scottish Parliament.
It follows a recent report from Audit Scotland which scrutinised NHS boards' management of waiting lists and treatment time targets after NHS Lothian was found to be manipulating waiting time codes in 2011.
While the auditor did not find further evidence of manipulation in other parts of the country, MSPs were told that health boards and the Scottish Government failed to heed early warning signs of problems with managing patient waiting lists.
Labour's Jackie Baillie said: "The Audit Scotland report makes clear that Nicola Sturgeon should have known about the hidden waiting lists over which she presided. She should have asked questions about the misuse of 'social unavailability' but either didn't or failed to act when told what was happening.
"Nicola Sturgeon needs to come to Parliament and explain what she knew, when she knew it and why she failed to act on the warnings. She sat through the ministerial statement on the Audit Scotland report but didn't speak. Now she needs to answer for her inaction."
Responding to Labour's comments, a Scottish Government spokesman said: "Scotland's NHS does a remarkable job and has made good progress in recent years in reducing waiting times. This is reflected by the 88% satisfaction rate that patients have in their waiting times.
"Audit Scotland's recent report also confirmed that there was no deliberate manipulation of waiting lists.
"Waiting times are currently the lowest on record and the NHS staff who have worked hard to get them there have our thanks.
"To continually suggest that they are trying to find ways not to give patients the best possible treatment is offensive and incorrect."