SNP treasurer Colin Beattie has been arrested by police investigating the party’s funding and finances.
Police Scotland did not name the arrested man but said a 71-year-old suspect was detained on Tuesday.
“The man is in custody and is being questioned by Police Scotland detectives,” the force said.
“A report will be sent to the Crown Office and Procurator Fiscal Service.”
It added: “As the investigation is ongoing we are unable to comment further.”
The development comes as the SNP continues to be rocked by the scandal surrounding the party’s finances.
Earlier this month, Peter Murrell, the SNP’s former chief executive and Nicola Sturgeon’s husband, was arrested in connection with the investigation into the party’s finances.
He was later released without charge pending further investigations after an 11-hour detention.
At the same time that he was in police custody, detectives seized a £100,000 motorhome from outside the home of one of Mr Murrell’s elderly relatives.
In another move that has hit the party, its long-standing auditors Johnston Carmichael quit just days after Mr Murrell’s arrest.
There have been questions hanging over new SNP leader and First Minister Humza Yousaf after he admitted that the party’s auditors had in fact quit months before the official announcement and he had not been aware at the time.
Asked whether it was wrong of Ms Sturgeon not to reveal to SNP leadership candidates the lack of auditors, Mr Yousaf responded: “Frankly it would have been helpful to know beforehand.
“I think people have a reasonable question to ask the party around transparency. I have committed to a review of governance with external input.”
Mr Yousaf also said he was unaware the SNP owned the motorhome until he became the party leader in recent weeks.
The new SNP leader – who billed himself as the “continuity candidate during the race to replace Ms Sturgeon – is facing pressure to distance himself from his predecessor over the ongoing scandal.
Over the weekend, a video emerged in which Ms Sturgeon appeared to tell the party’s ruling body to “be very careful” about suggesting the SNP was suffering from financial problems.
Mr Yousaf has faced calls to suspend Ms Sturgeon from the party following the video leak to the Sunday Mail.
Today he will address the Scottish Parliament for the first time since the Easter recess in a session Ms Sturgeon has said she will stay away from.
