Labour seems to be heading for "heavy losses" in council elections in Scotland while the SNP could become the largest party in two-thirds of local authorities, according to a new report.

A paper by elections expert Professor John Curtice for the Electoral Reform Society suggested Nicola Sturgeon's party could win most councillors in 23 of 32 local authorities.

The SNP won overall control of just two councils in 2012 - but the report suggests between seven and nine authorities could become targets.

Labour, which won overall control of four councils, including Scotland's largest authority Glasgow City Council, in 2012 "seems unlikely" to retain any, the report said.

A total of 1,227 council seats will be up for grabs on Thursday May 4 - with a total of 2,572 candidates in the running.

The SNP are fielding 627 candidates, an increase of 14 from 2012, and with the party targeting victory in Glasgow it is fielding 56 candidates in the city, 13 more than the last council election.

The Scottish Green Party has 218 candidates, a record number and 132 more than five years ago, while the number of Tory candidates is up 18 to 380.

In contrast, Labour has 44 fewer people standing than in 2012, with 453 candidates.

The number of Liberal Democrats and independent candidates is unchanged at 247 and 499 respectively, and there are 148 candidates from other parties.

Prof Curtice said: "The changes in the number of candidates being nominated by the parties give us a strong clue as to how they see their chances.

"The Greens, above all, are evidently hoping to make a significant breakthrough while the Tories and the SNP would seem to anticipate doing better than they did five years ago.

"Labour, in contrast, would appear to be expecting a setback.

"As a result of the sharp reduction in the number of candidates it is fielding, the party can only retain control of Glasgow, West Dunbarton and Renfrew if every single one of the party's candidates there secures election."

The report warned there could be "heavy losses" for Labour, stating the party "seems unlikely to retain control of any of the four councils where it won an overall majority in 2012".

It added: "Conversely, the SNP should retain control of the two councils that they won five years ago, Angus and Dundee."

While it is "more difficult" to identify authorities where the nationalists could seize overall control, the report said: "If the party were to increase its share of first-preference votes by the average of 10 points that it has enjoyed in local by-elections throughout the last two years, then taking into account the limitations on the proportionality of the system thanks to the use of three and four-member wards, the following seven councils would appear to possible SNP targets: Clackmannanshire; East Ayrshire; Midlothian; North Ayrshire; Renfrewshire; Stirling; West Lothian."

It also said Perth and Kinross Council could be added to that list "though a strong performance by the Conservatives there would doubtless significantly reduce the nationalists' chances while on a good day and with a measure of luck the party might just win South Lanarkshire".

The report went on: "If the SNP advance were to be a more modest five points, then perhaps it would gain control of no more than a couple of councils, most likely Clackmannanshire and West Lothian.

"Doubtless such a modest outcome would be regarded as a considerable disappointment by the nationalists.

"it should be borne in mind that such an advance could well be enough to see the SNP emerge as the largest party at least in another ten councils, including the three key cities of Aberdeen, Edinburgh and Glasgow.

"Such an outcome would mean the SNP would at least be the largest party (and sometimes in control) in 23 of Scotland's 32 councils."

Electoral Reform Society director Willie Sullivan said: "It's positive that by and large parties are putting forward more candidates than last time - and it means more choice and a stronger voice for voters under Scotland's proportional voting system.

"Clearly, parties are expecting change on Thursday - and it's likely voters' shifting support for parties will be reflected in town halls across Scotland."

A Scottish Labour spokesman said: "Voters at this council election face a choice - they can either elect a local champion with Scottish Labour, or a cheerleader for independence with the SNP.

"The SNP has cut £1.5 billion from local services since 2011. Communities want councillors that will stand up for them, not Nicola Sturgeon.

"Only by backing Scottish Labour can voters send Nicola Sturgeon a message that they do not want a divisive second independence referendum."

Susan Aitken, co-convener of the SNP's council election campaign, said: "It is clearer than ever - a vote for the SNP this Thursday is a vote to back vital local services and investment in our communities and a vote against further Tory austerity.

"This report suggests that the SNP's prospects are positive heading into the final week of our campaign, but we take absolutely nothing for granted and will continue getting our message out to the voters of Scotland until polling day.

"Only the SNP can stand up for the interests of our communities and deliver the public services that we all rely on.

"It is absolutely vital that people across Scotland vote SNP on Thursday to ensure that these public services continue to work in the interests of everyone."