WASHINGTON -  The US Senate's top Democrat blasted FBI chief James Comey Sunday for announcing a new review of Hillary Clinton's emails just days before the presidential election, an action he says "may have broken the law."

Allegations Clinton put the United States at risk by using a private email server while secretary of state were thrust back into the spotlight Friday when Comey revealed a renewed FBI probe into the matter based on a previously unknown trove of emails.

"As soon as you came into possession of the slightest innuendo related to secretary Clinton, you rushed to publicize it in the most negative light possible," Senate Minority Leader Harry Reid said in a statement.

"Through your partisan actions, you may have broken the law," Reid said, alleging that Comey had violated the Hatch Act, which bars the FBI from influencing elections. Clinton has demanded the FBI director explain in detail why he had effectively reopened an inquiry declared complete in July, branding Comey's move "deeply troubling" so close to Election Day.

According to US media, the probe was renewed after agents seized a laptop used by Clinton's close aide, Huma Abedin, and her now estranged husband, Anthony Weiner. The disgraced former congressman who resigned in 2011 after sending explicit online messages is under investigation over allegations he sent sexual overtures to a 15-year-old girl.

Both Clinton and her Republican rival Donald Trump have piled pressure on Comey to put his cards on the table and end speculation about the investigation before America goes to the polls on November 8.

According to CNN, discovery of the emails occurred weeks ago although the FBI did not reveal the matter until Friday. While Clinton is still overwhelmingly expected to win the ballot, polls - many of which were taken before the FBI email announcement - showed the US election tightening Sunday.

In the same memo, Reid also struck out at the FBI chief for sitting on "explosive information about close ties and coordination between Donald Trump, his top advisors and the Russian government."

"I wrote to you months ago calling for this information to be released to the public," Reid said.

Meanwhile, the US Federal Bureau of Investigation has obtained a warrant to review a tranche of newly-discovered emails that could be related to the previously-closed investigation of Hillary Clinton’ handling of classified information, according to American media reports.

An official, who is not authorized to comment publicly, was cited by the media as saying that the process had begun to seek an expeditious review of emails linked to longtime Clinton aide Huma Abedin, a US-born Muslim-American raised in Saudi Arabia by a Pakistani mother and an Indian father. Though the volume of emails is substantial - perhaps in the thousands - authorities have not completely ruled out the possibility of completing the review by Election Day.

It is possible that many of the emails, discovered during a separate investigation of Abedin’s estranged husband former New York Congressman Anthony Weiner, are duplicates of those already reviewed by the FBI, the official said.

Weiner is suspected of having sexually charged communications with a 15-year-old girl.

Meanwhile, a Justice Department official said that although Attorney General Loretta Lynch objected to FBI Director James Comey’s decision to notify Congress of the new email discovery, Justice officials would be supporting the FBI action to resolve the matter as quickly as possible.

The Clinton campaign said Sunday that neither Abedin nor her lawyer had been contacted by the FBI.

The Wall Street Journal reported Sunday that there may be as many as 650,000 emails on the laptop, but it is unclear how many may be relevant to the Clinton email server investigation.

FBI Director James Comey announced Friday that the bureau had uncovered emails that may be related to the FBI probe of Clinton's use of a private email server while she was secretary of state. Comey had announced in July that while Clinton had mishandled classified information on her private email, he would not recommend criminal charges against her.

Ever since, the Democrats have been accusing Comey of trying to impact the result of the election under pressure from Clinton’s Republican opponent, Donald Trump, as well as other Reopublicans.

"They have 650,000 they have found, it was just reported," Trump said at a rally in Greeley, Colorado. "I would think they will have some real bad ones, but we're going to find out. Maybe not, maybe not."

Meanwhile, US Senate Democratic leader Harry Reid sent a letter to the FBI chief, accusing him of attempts to change the course of the election through violating the Hatch Act.

Former Attorney General Eric Holder has also joined hands with dozens of other former federal prosecutors by signing a letter to censure Comey’s move.