An FBI roiled by brutal internal strife is about to sift through 650,000 emails it found on Anthony Weiner's laptop

The FBI will investigate some 650,000 emails found on disgraced former congressman Anthony Weiner's laptop that may be relevant to a probe into Hillary Clinton's private email server, The Wall Street Journal reported Sunday night.

The Journal report cited sources familiar with the investigation to say that metadata within the messages suggests thousands could have been sent to or from Clinton's private email server.

The messages were uncovered after investigators seized devices allegedly used by Weiner, the estranged husband of top Clinton aide Huma Abedin, to exchange sexually explicit texts with underage girls.

The Clinton email server investigation was completed in July, with FBI Director James Comey recommending no criminal charges against Clinton for her use of the server while she was secretary of state. But in a vague letter addressed to congressional leaders released on Friday, Comey announced the discovery of more emails "that appear to be pertinent" to the Clinton investigation.

The bureau came under fire over the weekend after a Washington Post report revealed that agents had known about the emails since early October, but chose not to tell Comey about them until fewer than two weeks before the presidential election.

Developments over the weekend, meanwhile, have laid bare internal strife both within the FBI itself and between the FBI and Justice Department in multiple inquiries involving Clinton.

The Justice Department reportedly asked the FBI not to disclose the discovery of the new emails to Congress so close to Election Day, but Comey wrote to his employees on Friday that he felt "an obligation to do so given that I testified repeatedly in recent months that our investigation was completed."

Some within the FBI have apparently been unhappy with Comey's tendency to overshare various aspects of the Clinton investigation with lawmakers and the public, stemming back to the unprecedented press conference the director gave in July to announce that the FBI would not recommend criminal charges in the case.

Agents were also frustrated with the FBI leadership's apparent disinterest in aggressively investigating the Clinton Foundation for possible conflicts of interest and financial crimes, according to the Journal.

The Foundation's controversial donation practices came under renewed scrutiny last week when WikiLeaks published a hacked memo titled "Bill Clinton, Inc." that raised questions about the blurring of lines between the charity and the Clintons' personal finances.

With no solid evidence of criminal wrongdoing, however, prosecutors within the public-integrity section of the Justice Department - who are not politically appointed - worried that they would be perceived as trying to influence the outcome of the election if they pursued the Clinton Foundation investigation. As such, they reportedly pressured FBI leadership to drop the Foundation probe.

Adding to that perception over the weekend was the revelation that the FBI had not obtained a separate warrant to sift through the roughly 650,000 Clinton emails found on Weiner's laptop before announcing on Friday that they existed. Weiner's laptop, which he evidently shared with Abedin, was subpoenaed in late September. The FBI eventually obtained a warrant over the weekend.

Clinton's email scandal has dogged the Democratic presidential nominee for more than a year. In March 2015, she first admitted to exclusively using a private email account to send and receive work-related emails while she served as secretary of state. The controversy compelled her to hand over roughly 30,000 work-related emails to the State Department, which have been released in batches since last year.

But she deleted about 30,000 additional emails from her server that she said were "personal" in nature before handing it over to the FBI in August, five months after she gave individual emails to the State Department.

Republican presidential nominee Donald Trump, seizing on the issue over the weekend, said during a Sunday rally that the FBI may have reactivated the Clinton investigation because they found some of those 30,000 deleted emails. He described them as the potential "mother lode" that could bring down Clinton's candidacy.

Reports have indicated, however, that many of the Abedin emails, going back years, passed through Clinton's inbox at some point and were therefore already examined by agents who investigated her server from August 2015 through July 2016.

When asked during a congressional hearing in July if he would reopen the investigation if he "discovered new information that was both relevant and substantial," Comey replied that the FBI "would certainly look at any new and substantial information."

Clinton implored the FBI on Friday evening to release more information about its review of the newly discovered documents, and her campaign has continued to go on the offensive over the weekend.

"The American people deserve to get the full and complete facts immediately," she said at a press conference.

It is unclear whether the FBI will complete its probe of the new emails before November 8.