LABOUR has been criticised for breaking the rules on postal votes in last year's Glasgow North East by-election and for leaving constituents there without an MP for more than four months.
The report by election watchdog the Electoral Commission said Labour had held on to postal vote applications for up to four weeks longer than the two days allowed.
The report also pointed out that one in 20 postal vote applications had been rejected on polling day and that Strathclyde Police are still investigating a case of personification, where people allegedly tried to vote in the names of persons who were marked as already having voted on the electoral register, although this has not been linked with any party.
John McCormick, the Electoral Commissioner for Scotland, said lessons on postal votes would need to be learned in time for this year's general election. However, he acknowledged there had been problems caused by a mail strike, which Labour said caused the delay in passing on postal vote applications.
Some of Mr McCormick's strongest criticism was over the delay in holding the by-election, which took place four and a half months after Speaker Michael Martin stepped down from his seat. The report noted this was the longest timelag for 35 years in a by-election being called.
Mr McCormick pointed out that by-elections for the Scottish Parliament and Welsh Assembly had to be held within three months unless there was to be a general election for those institutions within six months.
He said the last time the timing of by-elections was reviewed was at a Speaker's Conference in 1973, and added: "The UK parliament should reconsider the procedures for calling a UK parliamentary by-election to ensure that electors have an opportunity to elect a new MP promptly."
Labour's opponents – the party won Glasgow North East by more than 8,000 votes – have described the report as "deeply worrying".
SNP campaign co-ordinator Stewart Hosie said: "It is almost beyond belief a major political party would so blatantly breach the code of conduct on postal voting.
"Labour needs to explain why they held on to postal vote applications beyond the two working days allowed; indeed, why they did not submit some of them for almost a month."
He went on: "The people of Glasgow North East were left without an MP for an astonishing 142 days because of the shocking arrogance of the Labour Party, who put their electoral convenience ahead of the needs of the local community."
The Liberal Democrats' spokesman on Scotland, Alistair Carmichael, said: "By-elections should be called for the convenience of the public, and not for the political advantage of the party holding the seat. Reform of this is long overdue."
However, Labour pointed out that the SNP had been highly critical of a decision to hold the 2008 Glasgow East by-election during the Glasgow Fair. Alex Salmond described it as "outrageous".
A Labour spokesman said: "For the SNP to now complain about not holding the (Glasgow North East] by-election in the school holidays is sheer desperation.
"The Recess Elections Act (1975) stipulates that where an MP resigns his or her seat, the by-election must take place within 16 to 19 parliamentary days of the writ being moved, but the writ cannot be moved during recess. If the writ had been moved before the recess, the by-election would have had to have been held during the Glasgow school holidays.
"The only alternative was for the writ to be moved as soon as parliament returned from recess – or to arrange an emergency recall of parliament at huge cost."