The FBI sent a letter to the Senate Judiciary Committee in an effort to clarify director James Comey's testimony about emails belonging to Huma Abedin.

In the Tuesday letter, the FBI says that Abedin — a former aide to Hillary Clinton— only manually forwarded two email chains containing classified information to the account of former New York Rep. Anthony Weiner. The letter is not signed by Comey, but rather by Gregory Bower, assistant director in the office of congressional affairs.

In his testimony before Congress last week, Comey said Abedin deliberately "forwarded hundreds and thousands" of emails to her husband's account.

On Monday night, ProPublica reported that the FBI knew Comey misstated what FBI investigators found that Abedin did and was preparing to correct his mistake.

The FBI said in its letter that it believes "most of the emails" found on Weiner's laptop — roughly 49,000 — occurred as a backup from other devices.

In his testimony, Comey said the notion that announcing in late October that the FBI was reopening its investigation into the Clinton email scandal influenced the election made him "mildly nauseous." But, he said he would still make the same decision to do so today.

Comey is set to testify before the Senate Intelligence Committee on Thursday about global threats.