A 42-year-old woman has filed a complaint with the NYPD alleging high-powered attorney Sanford Rubenstein sexually assaulted her in his East Side apartment, NBC 4 New York has confirmed.

Law enforcement sources say the woman's complaint is under investigation by the NYPD's Manhattan Special Victim's Unit. Investigators were seen carrying bags of evidence out of Rubenstein's apartment Sunday night and Monday. 

Rubenstein has not been charged, law enforcement sources said. His attorney, Michael Ross, said, "Sanford Rubenstein vehemently denies any misconduct."

Ross and Benjamin Brafman, who is also representing Rubenstein, said Sunday, "We are confident that when the investigation is completed, it will be closed without the filing of any criminal charges."

The woman claimed to police she was assaulted after going back to Rubenstein's apartment after the 60th birthday bash for the Rev. Al Sharpton Wednesday night at The Four Season restaurant. Aretha Franklin, Spike Lee, Gov. Andrew Cuomo and Mayor de Blasio were among the guests at the party. 

In addition to filing a complaint with police, sources said the woman also went to the hospital to be evaluated.

De Blasio said the allegations were troubling. 

"But let's be clear: There is an investigation going on, and, to the best of my understanding, there are not formal charges yet. We have to treat everyone equally. We first have to see where the justice goes with this, and then, of course, there will be due process,'" he said. "I don't think there's a lot we can conclude until the investigation runs its course.''

Sanford Rubenstein is famous in part for his lawsuits on behalf of police brutality victims including the infamous case of Abner Louima. He is also representing the family of Eric Garner, the 43-year-old Staten Island father who died in police custody after being put in a chokehold.

A spokesman for the NYPD declined to comment.

Rubenstein is a member of the National Action Network and has often stood arm-in-arm with Sharpton at protests.

Sharpton said Monday, "Sandy and I have become friends, but the young lady that made the accusation is a top official. Sandy has no official capacity with me, she does. I respect her and she has been very, very helpful to us. So we're between the situation." 

Sharpton runs the National Action Network and is a talk-show host on MSNBC, which is owned by WNBC's parent company, NBCUniversal.

Follow Jonathan Dienst on Twitter @jonathan4NY