The husband of Scotland's former first minister Nicola Sturgeon has been arrested in connection with an investigation into Scottish National Party finances.
Peter Murrell, 58, is being questioned after being taken into police custody on Wednesday morning.
Police Scotland said officers were carrying out searches at a number of addresses as part of the investigation.
He has been married to Sturgeon since 2010.
A spokesperson for the former first minister said she had "no prior knowledge" of Police Scotland's action or intentions.
"Ms Sturgeon will fully cooperate with Police Scotland if required, however at this time no such request has been made," the spokesperson said.
Sturgeon stood down as first minister last month and was last week succeeded by Humza Yousaf.
The new first minister said it was "a difficult day" for the SNP.
Yousaf said: "I obviously can't comment on a live police investigation.
"But what I will say is that the SNP has fully cooperated with the investigation and it will continue to do so."
He added that the party had agreed to carry out a review on governance and transparency.
There has been police activity at Murrell and Sturgeon's home in Glasgow and at SNP headquarters in Edinburgh.
Police Scotland said Sturgeon was at the house when officers arrived at 7.35am to arrest her husband.
By 10am, there were 10 uniformed officers stationed outside the couple's detached property, along with three police vehicles.
The house was sealed off with blue and white tape, while a tent was erected on the driveway. Items were brought from the house to the tent, where the BBC understands a vehicle was parked.
Police officers could be seen searching a small shed and storage box in the back garden, a police photographer took pictures and officers looked at a laptop.
The curtains and blinds remained drawn and there was no sign of anyone in the property.
Meanwhile, at least six marked police vehicles were parked outside SNP HQ and officers carrying green crates and other equipment were seen going inside.
In the afternoon, two vans left the city centre building, while police officers remained stationed outside.
In July 2021, Police Scotland launched a formal investigation into the SNP's finances after receiving complaints about how donations were used.
Questions had been raised about funds given to the party for use in a fresh independence referendum campaign.
Seven people made complaints and a probe was set up following talks with prosecutors.
Sturgeon, then first minister and SNP leader, had insisted that she was "not concerned" about the party's finances.
She said "every penny" of cash raised in online crowdfunding campaigns would be spent on the independence drive.
According to a statement, the SNP raised a total of £666,953 through referendum-related appeals between 2017 and 2020. The party pledged to spend these funds on the independence campaign.
Questions were raised after its accounts showed it had just under £97,000 in the bank at the end of 2019, and total net assets of about £272,000.
Last year, it emerged Murrell gave a loan of more than £100,000 to the SNP to help it out with a "cash flow" issue after the last election.
The then SNP's chief executive loaned the party £107,620 in June 2021. The SNP had repaid about half of the money by October of that year.
At the time, an SNP spokesman said the loan was a "personal contribution made by the chief executive to assist with cash flow after the Holyrood election".
He said it had been reported in the party's 2021 accounts, which were published by the Electoral Commission in August last year.
Weeks earlier, MP Douglas Chapman had resigned as party treasurer saying he had not been given the "financial information" to do the job.
Murrell resigned last month after taking responsibility for misleading statements about a fall in party membership.
The number of members had fallen from the 104,000 it had two years ago to just over 72,000.
An SNP spokesperson said: "Clearly it would not be appropriate to comment on any live police investigation but the SNP have been cooperating fully with this investigation and will continue to do so.
"At its meeting on Saturday, the governing body of the SNP, the NEC, agreed to a review of governance and transparency - that will be taken forward in the coming weeks."
Scottish Labour leader Anas Sarwar told BBC Scotland it was "an extremely serious situation" and that the police investigation must be allowed to proceed without interference.
"But there are huge questions I think to answer for both Humza Yousaf and Nicola Sturgeon about what they knew and when," Sarwar said.
Scottish Conservative leader Douglas Ross said: "This is clearly a very serious case and it's absolutely crucial now that those at the top of the SNP, including Humza Yousaf and Nicola Sturgeon, co-operate fully with this ongoing police investigation."
Alba leader Alex Salmond, who preceded Sturgeon as first minister and SNP leader, told BBC Scotland: "I led the SNP for a long time. I'm very sad about what's happening to it and indeed about what it has become."
- BBC