JO Swinson, the deputy leader of the UK Liberal Democrats, is being investigated by the police over her general election spending.

The East Dunbartonshire MP, who was a minister in the Coalition government, is understood to have been reported by a constituent last week.

Police Scotland confirmed an initial complaint had been received and preliminary enquiries were underway.

Ms Swinson, 37, has faced questions about her election spending since August, when the Herald revealed she scraped in £210 below the spending limit of £14,619.

However this was only after almost £7000 of costs were disregarded.

READ MORE: MP Swinson under fire over 'vanishing' election costs

Despite fighting the top LibDem target seat in Scotland, her official candidate return said £2700 of voter literature was left undelivered and so did not count towards the total.

The declaration said more than 93,000 items were never used, including 26,000 copies of Ms Swinson’s main newsletter, the four-page full colour East Dunbartonshire Standard.

Another £4040 of leaflet, staff and office costs were attributed to “national” spending promoting the LibDems in general, rather than Ms Swinson as the local candidate.

No other candidate in the constituency split their spending down national and local lines.

READ MORE: MP Swinson under fire over 'vanishing' election costs

It is an offence punishable by a year in prison to knowingly submit a false spending return.

Mr Swinson, who was East Dunbartonshire MP for a decade until defeat in 2015, regained the seat from SNP’s John Nicolson in June by 5339 votes.

She became deputy leader of the LibDems a fortnight later.

Christine Jardine, the LibDem MP for Edinburgh West, was reported to the police over her general election spending three months ago.

Alex Cole-Hamilton, the LibDem MSP for the Holyrood seat of Edinburgh Western, was investigated for a year over his 2016 election expenses.

Last month the Crown Office announced there would be no proceedings against him.

READ MORE: MP Swinson under fire over 'vanishing' election costs

A LibDem spokesperson said: “All expenditure in this election was apportioned correctly and clearly identified in our election return which is a matter of public record. We have full confidence that there is no substance to this complaint.

“We make no apology for fighting as hard as we could to stop the SNP in their tracks. The people of East Dunbartonshire made a clear choice when they rejected the SNP in June.”