Investigators have found that electronic counting systems were not to blame for the huge volume of rejected ballot papers that marred Scotland’s parliamentary and local government elections in May.

Around 142,000 ballot papers for the Scottish parliament elections were rejected – 3.5% of the total votes cast. Results were also delayed after problems with new computerised counting technology.

But a report by independent investigators, led by Canadian expert Ron Gould, commissioned by the Electoral Commission says: “It is important to note that our assessment has not found any evidence that the electronic count contributed to the number of rejected ballot papers.”

It adds that if the complex single transferable vote (STV) system used in the Scottish polls is here to stay then electronic counting “cannot be reasonably abandoned”.

“While there were some problems with the electronic count on the night of 3 May 2007, such as the database malfunction specific to the DRS system that occurred at some counting centres, there is little doubt that the electronic count facilitates the counting of STV ballot papers and, in this respect, is preferable to a manual count,” the report says.

But the report warns: “The confidence that electoral stakeholders have traditionally had in the counting process was shaken on the night of 3 May 2007.”

Electronic voting for the 2011 elections should not be introduced until the electronic counting problems from the 2007 elections are resolved, it recommends.

Until electronic counting and other election technology “has been tried, tested, proven and
unchanged over the course of several elections”, the report suggests a full manual back-up system should be lined up, to “be implemented quickly in instances where technology simply does not work as planned”.

Investigators found that delays in the election planning cycle that resulted in the election “being partially driven by the technology rather than those responsible for the overall policy and management of elections”. It also warns that the legislative and policy frameworks for electronic counting are “underdeveloped”.

A “database malfunction” in the systems supplied by specialist form DRS had delayed the results of the election, with the impact varying at different counting centres.

But the report focuses its fire on the wider preparations for the election, saying party leaders and public officials had “treated voters as an afterthought", with crucial factors such as the design of ballot papers making the election more difficult for the electorate.

Its publication has seen former Scottish secretary Douglas Alexander apologise for his role in the fiasco and a stormy debate in parliament.

In an earlier report independent observers warned of problems with electronic voting as well as counting technology piloted in the May elections in England.