The police have been investigating leaks from the Home Office
The offices, home and car of Tory MP Damian Green have been swept for listening devices by a private security firm called in by his own party.
The Tories feared police investigating alleged leaks of sensitive Home Office material may have planted bugs when they raided the premises last week.
Despite intensive searches, nothing was found by the security experts.
The MP was held by police last week on suspicion of conspiring to commit misconduct in public office.
It is understood a Berkshire-based security firm was hired to carry out the search.
The Metropolitan police, whose officers arrested Mr Green last week, has declined to comment on the search.
Using electronic devices, the experts swept Mr Green's constituency home and association offices in Bethersden, Kent, on Friday.
The day before, a similar sweep had been carried out at the MP's London residence, Westminster office, and his previously impounded car.
Mr Green's agent Gordon Williams said: "Damian is very anxious to maintain the confidentiality of his electors' parliamentary case work.
"Clearly the offices in Bethersden were occupied for quite some time without us personally being present.
"We cannot guarantee the integrity of the office while we're not here, so to avoid the possibility of any listening devices being planted we decided to have the offices in Bethersden swept and also the parliamentary office, car and London and constituency homes."
Mr Williams confirmed no bugging devices were found in any of the searches.
Mr Green, the Conservative immigration spokesman, was arrested on 27 November over alleged leaks of sensitive Home Office material.
His controversial detention followed the 19 November arrest and then suspension of a 26-year-old junior official.
Mr Green has always insisted that he had been doing his public duty in holding the Government to account and would continue to do so.