PETE Wishart has renewed SNP's call for answers to dark donations to the Scottish Tories and said the questions "pile up at Ruth Davidson's."
The Electoral Commission is examining the Scottish Unionist Association Trust (SUAT) for its ties to the Scottish Tory party, having donated nearly £ 320,000 since 2001.
SNP MP Wishart urged Davidson to confirm whether SUAT donations went to the 2017 election campaigns of John Lamont, David Duguid and Douglas Ross, and whether spending on electoral expenses was carried out correctly.
The Ferret website, which broke the scandal for the first time, revealed that former Scottish Tory MP and Scottish shadow secretary Peter Duncan, a current SUAT trustee, has lobbied Tory MSPs on behalf of his communications firm Message Matters.
The Scottish Greens told the site that his position as Holyrood lobbyist and trustee of a Scottish Tories fund was "incompatible".
Questions were also raised regarding the status of SUAT as "liberated trust", with the electoral commission investigating whether a transfer of ownership of their Glasgow property disqualifies them.
If so, the donations to the Scottish Tories could be illegal.
Wishart called on the Commission to carry out a full investigation, saying that fines would not be a sufficient penalty for misconduct and called for "the forfeiture of donations".
He added, "At the door of Ruth Davidson, serious questions are piling up on the dark money that funds the Scottish Tories.
"Ruth Davidson needs to be clean and tell the public when donations from the Scottish Unionist Association Trust (SUAT) are channeled into Tory MPs John Lamont, David Duguid and Douglas Ross.
"The Scottish Tories must also show whether John Lamont, David Duguid and Douglas Ross have correctly completed the election reparations.
"It is time for the Electoral Commission to use its powers to tackle rule-breaking, fraud and dark money, and if the Commission detects misconduct, we have to collect donations and fines." We believe that the scale and scope of the SUAT Activities equal two sanctions. "
SUAT gave £ 7,500 to Banff and Buchan MP David Duguid and Moray MP Douglas Ross last year and donated £ 5,000 to Scottish Tory Deputy Jackson Carlaw before becoming MSP.
The criticism of the "dark money" comes from the lack of transparency about the funding sources for donations donated by SUAT.