Former chancellor Ken Clarke has told a court claims he molested a young actor were "like Martians landing".
Ben Fellows is on trial at the Old Bailey accused of making up a false claim against Mr Clarke.
The 40 year old alleged that the Conservative MP plied him with alcohol and carried out the sexual assault in the office of political lobbyist Ian Greer in 1994 while he was working as an undercover actor for ITV's Cook Report.
Giving evidence at the trial, Mr Clarke, 75, told jurors: "Apparently while chancellor of the Exchequer I was hanging around the office of Ian Greer and groped a man.
"My recollection was it was like Martians landing."
The MP for Rushcliffe, Nottinghamshire, told the court he "never had the compulsion" to grope a man, adding: "It's preposterous. It's off the Richter scale."
Mr Clarke said he was aware of the allegation before police visited him in June 2013 after his son spotted Fellows making claims online.
He said: "By the time the police arrived I was aware what there was on the internet and newspapers.
"This guy for some reason was making this allegation against me over and over again trying to publicise it."
Fellows, who Mr Clarke described as a "stalker", is accused of perverting the course of justice.
The trial continues.