Three police forces have been probing allegations that SNP MP Angus MacNeil was spied on.
Angus MacNeil has been subject to intrusion, Alex Salmond says
Nationalist leader Alex Salmond said the Western Isles MP who sparked the cash-for-honours inquiry had been subject to "intense intrusion".
Strathclyde and the Metropolitan Police said they had carried out probes but no crimes were detected.
Northern Constabulary said it was investigating a complaint about nuisance calls to the MP.
The allegations of spying followed revelations that Mr MacNeil had a "drunken romp" with two teenage girls.
A spokesman for the SNP said Strathclyde Police was alerted to allegations Mr MacNeil was subject to a "suspicious following operation" during the weekend of an SNP conference in Glasgow.
Strathclyde said an investigation took place but no crime was established and its inquiries were complete.
The Metropolitan Police also confirmed it had investigated an allegation of a break-in to Mr MacNeil's office in Westminster. A spokeswoman said that officers found no sign of an offence.
A SNP spokesman said the Northern force had been made aware of suspicious phone calls to Mr MacNeil's home on Barra on the Western Isles and the Metropolitan Police had checked the MP's office in the House of Commons.
Northern Constabulary said Mr MacNeil's Westminster colleague, Angus Robertson, had lodged a complaint about troublesome phone calls.
A spokesman said: "Northern Constabulary can confirm it has received a complaint from Angus Robertson MP regarding nuisance phone calls made to Angus MacNeil MP.
"The matter is under investigation and it would be inappropriate for the force to comment further."
During a visit to Stornoway on Monday night, Mr Salmond said the Western Isles MP had made the "most extraordinary powerful enemies" as a result of the honours inquiry.
He said police had investigated allegations that Mr MacNeil was being followed and incidents concerning his home on the islands.
The SNP leader also said there had been a "question of sweeping" Mr MacNeil's office in the House of Commons.
Mr Salmond said: "Angus MacNeil is somebody, because of leading the cash-for-honours inquiry, who has made the most extraordinary powerful enemies and I have never seen a member of parliament subjected to this sort of intense intrusion.
"I have to say, given what's been said by the families about the inaccuracies and exaggerations in the story that was printed, I think people around Scotland will be saying after all this investigation was that all they could dig up about him?"
The Sunday Mail newspaper reported that the married MP "kissed and fondled" the girls in a hotel room in July 2005.
Mr MacNeil said he bitterly regretted the incident and said he was angry it had diverted attention from the "substantial political issues" he had been pursuing.
In a statement, Mr MacNeil, 36, apologised for the "embarrassment and hurt" caused to his family by his actions.
The girls' families have claimed the story was exaggerated and inaccurate.