Police Scotland have launched an investigation into the finances of the governing Scottish National party following claims that it spent hundreds of thousands of pounds donated for a future independence referendum on other things.

The allegations highlight tensions within the Scottish independence movement over what some supporters see as the failure of Nicola Sturgeon, first minister and SNP leader, to deliver a rematch of the 2014 referendum in which Scots backed remaining in the UK by 55-45 per cent.

The investigation is also likely to focus attention on the internal management of the SNP, amid complaints from some members of inadequate transparency under the leadership of Sturgeon and her husband, party chief executive Peter Murrell.

“Police Scotland has now received seven complaints in relation to donations that were made to the Scottish National party,” the national force said on Tuesday. “After assessment and consultation with the Crown Office and Procurator Fiscal Service, we will now carry out an investigation.”

Some independence supporters have complained that the SNP raised £600,000 in donations in 2017 and 2019 specifically for use in a referendum campaign, but that while no such campaign has so far been fought, the party’s last publicly available accounts showed it had much less than that.

Documents published by the Electoral Commission in October showed that at the end of 2019, the SNP had less than £100,000 in cash and net assets of less than £300,000.

The SNP said it would co-operate fully with any investigation. “As we have made clear, all sums raised for independence campaigning will be spent on independence campaigning,” the party said.

Douglas Chapman, an SNP member of the UK parliament, resigned in May as party national treasurer, saying that despite having a “resounding mandate from members to introduce more transparency into the party’s finances”, he had not “received the support or financial information” to carry out the role’s fiduciary duties.

Sturgeon said in June she was not concerned about the handling of SNP finances, telling broadcaster STV that the party’s accounts were independently audited and money had not “gone missing”.

“We don’t hold separate accounts, we’re under no legal requirement to do that, our accounts are managed on a cash flow basis,” she said.

Sturgeon has faced criticism from more impatient SNP supporters who believe she has not pushed strongly enough for a second independence referendum since the Brexit referendum led to the UK’s exit from the EU, despite a 68-32 per cent vote in Scotland in favour of Remain.

The first minister has pledged to relaunch preparations for an independence referendum as soon as the coronavirus crisis is past, aiming for it to be held before the end of 2023.

UK prime minister Boris Johnson has made clear he will not approve a second referendum, but Sturgeon said her government is ready to try to hold such a vote under current devolution legislation, daring opponents to try to block it in the courts.

The opposition Scottish Conservative and Labour parties welcomed the police investigation into the SNP’s finances.

“The SNP have failed to be fully transparent over this funding for months. Senior figures have resigned from the party’s executive committee over the matter, but the SNP leadership have still not addressed these serious claims,” said Scottish Tory chief whip Stephen Kerr. “The public deserve to know the truth.”