Conservative MP Nadine Dorries is to take legal action over allegations contained in emails sent by Gordon Brown's former special adviser.
Ms Dorries was one of a number of Conservative MPs named in emails from Downing Street aide Damian McBride to other Labour activists about fictitious smear stories which could be spread on the internet.
Mr McBride was forced to resign after details of the messages became public earlier this month.
In a brief message on her website blog, Ms Dorries wrote: "I have instructed and proceeded with legal action.
"Obviously, I am not going to say anything at all at this stage, other than that."
The move comes after Ms Dorries secured a personal apology from Mr Brown when she confronted him at Prime Minister's Questions in the Commons on Wednesday.
After other Tories kept to their seats to ensure that the Mid-Bedfordshire MP was the only one to catch the Speaker's eye, Ms Dorries asked the PM: "Would you like to take this opportunity to apologise to me for what happened?"
Mr Brown replied: "Yes. And I have said sorry this has happened and I have also written to you personally."
