Patrick Grady's victim has said the Tories have put the SNP "to shame" with their handling of sexual misconduct complaints.
The SNP staff member, who is based at Westminster, said he did not want Grady, who is the former chief whip of the party, to think he was exonerated following the end of a police investigation.
It was revealed on Sunday that The Met announced that no further action was being taken against the Glasgow North MP after the victim decided not to assist the probe over fears it could create an "intolerable" working environment.
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Grady previously said he was "profoundly sorry" after a parliamentary inquiry found he acted inappropriately towards an SNP staff member.
The former chief whip of the SNP then resigned his party membership after police launched an investigation into the incident in a London pub in 2016.
Grady's victim said the party has taken a softer approach than the Tories, who withdrew the whip from MP Chris Pincher last week following accusations that he drunkenly groped two men at a private club in London.
The victim told the Scottish Daily Mail: "The SNP has been very quiet on the Pincher stuff - in normal times they would have been calling for his resignation.
"The Conservatives have put the SNP to shame with how they have handled Pincher."
He said he would be "more protected" as a Tory staff member than he is as an SNP worker.
"They (Conservatives) have taken effective action, kicked him out of his job, removed the whip, and it is now up to the independent complaints and grievance scheme to investigate," he said.
He added: "What the SNP has done with Patrick is totally different in that he kept the whip for the entire time, they kept him in the position of power and then isolated the victim and removed me from the equation."
The SNP staff member criticised the party's handling of the complaint. He said: "As things stand, I don't have to give Patrick any service as an MP.
"But if he is allowed back in at any moment that he decides, I'm not going to get fair warning of that - he could just turn up as an SNP MP if I go back to work.
"It is concerning because it is all in his hands now if he wants to come back.
"The SNP seem to have absolved any responsibility now, which, as an employer, is concerning.
"It wasn't me that even reported this to police. I don't know who did. I never wanted to take this route but now that it has, he suspended his own membership."
"I decided for it not to be investigated (by police) for fear it would impact on an already intolerable working environment," he added.
And he said the SNP are sending the "wrong message" by letting Grady decide if he would like to reinstate his party membership.
A spokesman for the Metropolitan Police said: "On Wednesday June 22 police received a third party allegation of sexual assault that is said to have taken place in October 2016 at a commercial premises in Folgate Street, E1.
"Officers carried out inquiries including speaking to the alleged victim.
"There will be no further police action at this time."
The SNP has said it would be up to Mr Grady to decide his "intentions" on returning to the party as he "currently sits as an independent MP".
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