Simon Danczuk has described an accusation against him of historical rape as "malicious, untrue and extremely upsetting".
The embattled Labour MP said he is confident he can clear his name, insisting he will co-operate with the police investigation.
The claim comes as the 49-year-old faces criticism over a separate incident involving lewd texts sent to Sophena Houlihan when she was 17.
Mr Danczuk, MP for Rochdale, has been suspended from the Labour Party while an investigation takes place into his conduct with regard to the sexually explicit messages, for which he has apologised "unreservedly".
In relation to the rape allegation a spokesman for Lancashire Police said: "We can confirm that we have received a report of a historic rape dating back to 2006.
"We are in the very early stages of an investigation and inquiries are ongoing. The complaint relates to a 49-year-old man."
Responding to the claims, Mr Danczuk said: "These claims are malicious, untrue and extremely upsetting.
"The police have not been in touch with me but I will co-operate fully with any inquiries and am confident my name will be promptly cleared."
The father-of-five's personal life has repeatedly made the headlines over the past year following the collapse of his marriage to wife Karen, who was dubbed the selfie queen after posting numerous photographs of herself in low-cut tops.
Around 20 protesters gathered on Monday at his constituency office calling for him to resign.
But Mr Danczuk dismissed the protest and said he believed the people of Rochdale want him to continue as their MP.
He claimed he was being "lambasted" for being a working class Boris Johnson, comparing his treatment in the media to that of the London mayor, saying there is an "establishment, class issue going on".
He said he should be allowed to "move on" from "mistakes" he has made. He has blamed a "drink problem" for his tangled personal life.
The MP's former partner, Claire Hamilton, said his admission of sending texts to Miss Houlihan led her to end their relationship shortly after Christmas, and that his drinking made it "harder and harder to be in the relationship".
Mr Danczuk described the last few months as "quite intense at times" and blamed some of his problems on depression brought on by his work campaigning against child sexual abuse whilst exposing the past of the town's former MP Sir Cyril Smith.
Meanwhile Mr Danczuk has admitted being paid to tip off a photo agency about opportunities to take photographs of him that could be sold to the media, receiving at least £1,115 from one.
The most recent Register of Members' Interests shows he received that sum from Fameflynet Ltd for approximately six hours of "media advice".
He told BBC2's Newsnight he provided "ideas about what they might and might not do".
He said: "That's my choice if I want to do that type of work and I don't make any apologies for it. It provides an insight, it provides some transparency in terms of my life.
"Of course I receive payment for that and I declare it properly."