Councils across Scotland have still to settle more than a third of all equal pay claims 13 years after the deadline for new rules was set, a spending watchdog has found.
The Accounts Commission said about £750m was spent settling claims since 2004 but nearly 27,000 were still live.
Councils were ordered in 1999 to "harmonise pay for employees and address historic inequalities".
But all but one of the 32 local authorities missed the 2004 deadline.
Responding to the report, the Convention of Scottish Local Authorities (Cosla) said councils "take their responsibilities to achieve equal pay very seriously".
It added that the findings recognised "the complex judicial processes and huge costs that councils have faced".
It took 11 years - twice as long as planned - for all councils to implement the equal pay agreement, which was finally completed in 2010.
The commission found progress was slowed by funding problems as councils received no extra money for the new pay scheme.
'Lack of national leadership'
Some approaches taken to save costs and avoid industrial action, such as protecting pay and bonuses for some roles, were also found to be discriminatory.
The report states: "Ultimately the measures councils adopted kept men's salaries higher than women performing equivalent roles."
The commission also found a "lack of collective national leadership to overcome the challenges and address equal pay issues in a timely way".
Between 2004 and 30 September 2016, some 70,453 equal pay claims were lodged against councils. Payouts, including compensation agreements and legal fees, totalled about £750m.
At the end of September last year, 26,912 equal pay claims lodged with the Employment Tribunal Service remained live - representing about a third of all claims since 2004.
Of these, nine out 10 are from women, and thousands of cases have been live for more than a decade.
The commission stressed that workers could potentially still make new claims against councils.
Most claims still live (National average - 37.4%):
- North Ayrshire - 95%
- East Dunbartonshire - 90%
- Falkirk - 80%
Most claims lodged:
- Glasgow City Council - 22,730
- North Lanarkshire - 10,480
- Edinburgh City Council - 6,163
- Orkney had the lowest at 14
Most paid out:
- North Lanarkshire - £129.9m
- Glasgow - £91.4m
- Edinburgh - £87.5m
- Orkney was lowest at £1.8m
The number of claims lodged and the cost of payouts varied, which the commission said could be due to size, the level of activity of "no-win no-fee" legal firms and approaches to handling equal pay issues.
Commission member Pauline Weetman said: "Equal pay is both an incredibly important issue and a legal duty for Scotland's councils to eliminate decades of inequality.
"However, implementation of equal pay has been a substantial challenge for local government.
"Councils need to be confident that pay equality is embedded in how they operate.
"It's critical that officers ensure that they're doing all they can to fulfil their duties in relation to equal pay and publicly report this work, and that elected members continue to scrutinise and challenge their progress."
'Nuanced legal issues'
Councillor Gail Macgregor, resources spokeswoman for Cosla, which represents many of Scotland's councils, welcomed the report.
She said it "recognises the complex judicial processes and huge costs that councils have faced as they have worked hard to meet their equal pay obligations".
Ms Macgregor added: "As employers, councils take their responsibilities to achieve equal pay very seriously, and we are frustrated that there remains a high number of claims outstanding.
"This is in large part down to complex and nuanced legal issues which can frustrate the process and act as barriers to quicker outcomes.
"Councils have endeavoured to settle all legitimate claims as quickly as possible. It is worth nothing that cases can remain 'live' in the Employment Tribunal system even when settled and we have no control over when these are taken down.
"Also, many other remaining cases are 'class actions' where the settling of a single test case will resolve a larger number of cases in one go."