New emails tied to the FBI's investigation of Hillary Clinton were discovered in a separate probe, in which the devices of former Congressman Anthony Weiner and Clinton aide Huma Abedin were seized, NBC News confirmed.
The New York Times first reported the news.
While examining Weiner's laptop, investigators discovered Abedin also used the laptop, which contained some emails between Abedin and Clinton, NBC News reported.
FBI Director James Comey said in a Friday letter to lawmakers that the agency is looking into the newly discovered emails.
The FBI has been examining text messages that Weiner sent to a minor in North Carolina that sources told NBC News included pornographic videos, requests for nudity and requests for masturbation. In September, law enforcement sources told NBC News that the investigation was in its early stages, but already included a subpoena for Weiner's cellphone records.
Weiner previously admitted "terrible judgment" in a statement to NBC News, but claimed he was the victim of a hoax.
Donald Trump previously lashed out at Weiner online, suggesting in one tweet that the former congressman was a security risk.
— NBC News contributed to this report.