POLICE are continuing to quiz Scottish Tory Party leader Ruth Davidson in connection with allegations pro-Union campaigners illegally counted postal votes in the weeks before independence referendum ballots closed.

Ms Davidson was interviewed by police in her Parliament offices last month, six days after Police Scotland was instructed by the Crown Office to carry out an investigation into alleged electoral secrecy law breaches.

Now it has emerged police have sought further clarity on what she told them in an exchange of emails. Party sources say the exchange, like the interview, was conducted on the basis of her being a witness and that Ms Davidson is not the subject of the investigation.

Police, who began assessing complaints two months ago, will only say the investigation is continuing. The formal police investigation was sparked after the Scottish Tory leader said on a televised discussion that postal vote "tallies" were being taken in the weeks before the referendum ballot closed at 10pm on September 18. Complaints over Ms Davidson's account of the postal vote "tallies" raised concerns the information may have helped inform the No campaign's decision to issue the "vow" of more powers for Scotland from the three main party leaders. Mary Pitcaithly, who is convener of the Electoral Management Board for Scotland, the official referendum scrutineer, has admitted for the first time that a "small number" made her aware of concerns the postal vote may have been compromised in the light of Ms Davidson's comments.

She says they were advised to raise any such concerns with their local counting officer who would be able to explain the steps taken to make everyone attending the opening sessions aware of the requirements for secrecy. "Anyone who called was also made aware that the matter had been referred to Police Scotland since only they could investigate any alleged breach of the criminal law.

"They were also made aware that they could themselves take any complaint or evidence to the police," she said.

"The behaviour of people entitled to attend postal vote opening sessions is a matter for the local COs in each area who will report any alleged breaches to the police. The CCO has no role in this but does issue guidance on the matter." A matter of days before details of the police assessment of complaints emerged Ms Pitcaithly announced that all counts "were properly conducted and scrutinised by thousands of people representing both the Yes Scotland and the Better Together campaigns, as well as international election observers, media and police."

She said then that nobody had raised any concerns during the verification, counting and adjudication stages.