Nadine Dorries has implied the Conservative Party conspired with the parliamentary expenses watchdog in order to prevent her getting the party whip back.
On Wednesday the Independent Parliamentary Standards Authority (Ipsa) announced Dorries had repaid £3,000 in travel expenses after accepting the claims were "wrongfully made and should not have been allowed".
However in a blog post, the MP for Mid Bedfordshire questioned the validity of the investigation. She said: "I suppose the big question is why, out of 649 other MPs, Ipsa chose to launch an expensive and time consuming investigation into my expenses, especially given that I have never claimed many of the expenses to which I was entitled."
"I am sure it is just a coincidence that, as the pressure began to mount for my whip to be returned after three months of suspension, wham, I surprisingly had an investigation in process. Any request for reinstatement met with the response from the Chief Whip 'we now have to wait for the Ipsa investigation to end'.
"Funny that no longer seemed important the morning after Ukip did so well in the local elections and I suddenly got my whip back, whilst the Ipsa investigation was still in process."
Dorries added that the money she had claimed incorrectly had been "a technical breach that was Ipsa's fault" rather than any attempt to defraud the public.
The outspoken MP was suspended from the Conservative Party following her decision to appear on the 'I'm A Celebrity Get Me Out Of Here' TV programme.
However she was eventually allowed to re-join the party in early May, just days after Nigel Farage's Ukip received a surge in support in local elections.
It had been suggested that Dorries, a harsh critic of David Cameron and George Osborne, could defect to the eurosceptic party and that she was only allowed to rejoin the Tories to prevent it.