High Peak MP Ruth George said the tweets from the now deleted account were posted without her knowledge.
One of the tweets from October said: "I enjoyed Theresa May's LABOUR party speech at #CPC16 today. So much better than Mein Fuhrer Amber Rudd yesterday."
A "passionate" campaigner had posted the tweets, Ms George's spokesman said.
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Ruth George became an MP when she took the seat from Conservative Andrew Bingham winning by a majority of 2,322 votes.
However, a number of controversial tweets from an account named Ruth for High Peak, which also had her picture attached, have since emerged.
A post comparing Amber Rudd to Hitler was in reference to her 2016 Conservative Party conference speech about foreign workers.
A tweet from July 2015 asked, "Is Theresa May a bloke? Is David Cameron human?"; and another talked about a "purge of nasty MPs" after Jeremy Corbyn was re-elected as Labour leader in September.
When Ms George was shown the tweets by the BBC she replied: "Good grief!"
She said: "They've got the wrong person, I don't tweet, well, certainly before this election.
"I think when somebody set up Ruth for High Peak at the start of the campaign [they] changed what was already there...
"I had no idea any of that was on there."
Ms George's press spokesman said it would have been "impossible" for her to be associated with the posts as the Ruth for High Peak account had a completely different name when the tweets were published in 2015 and 2016.
"Prior to 15 May 2017 the account that made the tweets was called @thecornerback and was completely not associated with Ruth in any way."
He added: "A very passionate campaign volunteer set up an account because he wanted Ruth to be MP... It's not Ruth's account."
However, on Ms George's personal twitter account, @ruthgeorge6, her profile stated she also "tweets as @ruthforhighpeak" - where the controversial messages were posted. This has since been amended.
The account also appeared to show Ms George had voted to leave the EU, when actually she campaigned to remain.
A newly-elected Labour MP has distanced herself from a Twitter account apparently in her name in which the home secretary was compared to Hitler.