The FBI is declining to comment on newly emerged documents that appear to show the agency investigating allegations that Sen. Bob Menendez "received the services of young prostitutes" while in the Dominican Republic -- a charge the senator's office has rejected for months.

His office continued to dismiss the report after dozens of pages of emails were posted online this week, appearing to show the FBI communicating with the individual claiming to know about Menendez' liaisons. The emails refer to an "investigation," and said "we have been able to confirm most of" the information provided and "know that you are providing accurate information."

It's unclear what "information" that line was referring to. The source's emails, though, along with recent reports from The Daily Caller, allege that Menendez, D-N.J., during trips to the Dominican Republic with a campaign contributor, saw prostitutes. Two women told the Caller, in a story published in November, that he paid them for sex.

"This is the same unsubstantiated garbage that's been peddled for months," a spokeswoman for Menendez told FoxNews.com in an email Friday.

FBI spokesman Jason Pack said he could not confirm whether there was an investigation. "DOJ policy prohibits us from confirming the existence or not of an investigation," he said.

However, Melanie Sloan, executive director of Citizens for Responsibility and Ethics in Washington, confirmed to FoxNews.com that her organization forwarded information on this issue to the FBI's Washington office and Justice Department criminal division on July 17, 2012.

"I believe that they started an investigation based on the information we forwarded," she said. Correspondence between the supposed source and CREW was also posted online this week. Sloan confirmed the authenticity of those emails.

Still, Sloan raised concerns about the credibility of the source, saying she is "increasingly suspicious" about the alleged facts in the case.

"He refused to ever be contacted by us by phone," she said. "It's really easy to make a lot of allegations. ... Who knows ... if that's even a real person."

She said CREW is no longer investigating.

The incidents reportedly involved at least one underage girl. In one of the emails, the source tells the agent he's passing a note from one of the girls who "participated in the private activities with the Senator Bob Menendez."

"She's 19 now, but took part in private parties with Senator Menendez being only 16," the email said.

Prostitution in the Dominican Republic is legal, but the age of consent is 18. Under the 2003 PROTECT Act, it is also a U.S. federal crime to "engage in illicit sexual conduct" abroad with anyone under 18 -- that includes prostitution.

The supposed source in all this goes by the name of Peter Williams. The individual did not return a request for comment from FoxNews.com.

According to email exchanges posted online, Williams has over the past year discussed his claims with the FBI, CREW and a producer with ABC News. The emails show CREW passing the case to the FBI, and a purported FBI agent in Miami reaching out to Williams in August.

The purported FBI agent, in the emails, expressed interest in speaking with the women, as well as meeting with Peter Williams.

It's unclear whether the meeting took place. The agent in late November emailed about traveling to the Dominican Republic, but Williams subsequently wrote about "setbacks." As of a December exchange, the FBI agent was still requesting a meeting with the source.

The Senate ethics committee had no comment on the latest documents.