A report has strongly criticised Scottish ministers in Westminster and Edinburgh for their decisions in the run up to this year's Holyrood elections.

An independent review by Canadian elections expert Ron Gould concluded that 146,099 parliamentary ballot papers were rejected, and a further 38,352 rejected papers in local elections, which took place at the same time.

Blame for the fiasco is heaped on the decisions of ministers in the Scotland Office and the then Labour/Liberal Democrat-controlled Scottish Executive.

The interests of voters were an "afterthought," said the report, while ministers were focused on "partisan political interest".

"At worst, the ministers disregarded the highly negative disruptive influence on the elections caused by their delays in arriving at key decisions," it added.

"At best, they either overlooked or were poorly advised with regard to the serious operational consequences that could and did result."

The elections saw the introduction of a a new design for the Holyrood voting paper and a new proportional voting system in the council ballots.

And both sets of elections were counted electronically for the first time in Scotland.

The study found that the run up to the elections were marked by changes "introduced with the expectation that they would simply fall into place by the date of the election, regardless of when decisions were made".

"This happened because there was no effective planning process or document which would have connected the legislative timetable to the operational timetable and provided early warning of problems ahead," it added.

To prevent such confusion arising in future, said the report, there should be a chief returning officer for Scotland, while the "logical" move would be to transfer all responsibility from Westminster to Edinburgh.

It also concluded that Scottish Parliament and local elections should be held on different dates, preferably around two years apart.

And to reduce voter confusion the local constituency and regional Scottish Parliament ballots should be on separate papers, it added.

The report also highlighted concern that although returning officers have legal responsibility for elections, they lack  "practical authority," given their reliance on on external suppliers.