Kourtney Kardashian, who has been hit with a paternity lawsuit by model Michael Girgenti claiming that he is the father of Kardashian’s eldest child, Mason Disick, is fuming over the allegations, a source told Radar Online.

Rumors of Girgenti being Mason’s father emerged early this year when he told the media of a supposed relationship with Kardashian in 2009, nine months before Mason was born. Girgenti said he has always suspected Mason to be his son, and attempts to establish contacts with Kardashian to voice his concerns have been rebuffed.

“This whole thing is so ridiculous,” the source close to Kardashian told Radar Online. “She thinks it is stupid and it really isn’t true.”

The source added that Kardashian is sure Girgenti is not Mason’s father as “she did not have sex with that model.”

Kardashian’s lawyer, Todd Wilson, told TMZ that although they haven’t had access to the paternity lawsuit documents, he believes Girgenti has been paid to spread lies about Kardashian.

“This individual has been selling false and fabricated stories to the tabloids for years about Kourtney Kardashian and her son, Mason. Scott Disick is Mason’s father. We have not seen the reported court filing, but we are informed that this individual has been seeking to get paid to publish his ridiculous pleading,”

“His claims are absurd and this is simply another shameful attempt to gain publicity and profit from fictional stories about my client," Wilson added.

According to TMZ, Girgenti filed the paternity lawsuit in Los Angeles County Superior Court on Thursday, requesting joint custody of Mason and seeking DNA tests for Kardashian, her partner Scott Disick, Mason and himself. The hearing has been set for next month.