FBI Director James Comey sent a letter to Congress informing them he is re-opening the case into Hillary Clinton’s private email server during her time as Secretary of State.

It's investigating whether new emails that have emerged may contain classified information.

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The FBI said in July its investigation was finished.

The Democratic presidential candidate's campaign has not commented on the FBI's announcement.

Her rival Donald Trump praised the FBI's decision to investigate during a rally in Manchester, New Hampshire.

"Perhaps finally justice will be served," Trump told the crowd.

Read FBI Director James Comey letter below:

"In previous congressional testimony, I referred to the fact that the Federal Bureau of Investigation (FBI) had completed its investigation of former Secretary Clinton's personal email server. Due to recent developments, I am writing to supplement my previous testimony.

In connection with an unrelated case, the FBI has learned of the existence of emails that appear to be pertinent to the investigation. I am writing to inform you that the investigative team briefed me on this yesterday, and I agreed that the FBI should take appropriate investigative steps designed to allow investigators to review these emails to determine whether they contain classified information, as well as to assess their importance to our investigation.

Although the FBI cannot yet assess whether or not this material may be significant, and I cannot predict how long it will take us to complete this additional work, I believe it is important to update your Committees about our efforts in light of my previous testimony.

Sincerely Yours

James B. Comey