WASHINGTON: The FBI today said it has reopened investigations into Hillary Clinton 's use of private email server when she was secretary of state due to likelihood of new information coming to light, immediately drawing praise from the White House frontrunner 's Republican rival Donald Trump FBI Director James Comey , in a communication to the Congressional leadership, said the FBI has learned of new "emails that appear to be pertinent" to their investigation."In connection with an unrelated case, the FBI has learned of the existence of emails that appear to be pertinent to this investigation," Comey wrote in the letter."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," Comey said.Clinton has previously apologized for using a private email server as secretary of state between 2009 and 2013 during the first term of President Barack Obama. Her act was criticised as tantamount to compromising national security.The FBI announcement today was an unexpected development just ahead of the November 8 US presidential election in the race to which several opinion polls have indicated Clinton was ahead of Trump and her lead was moving northwards decisively.Clinton's lead accelerated after her confident showing in the three presidential debates, in all of which she was declared the winner by American media.But the FBI's decision to reopen the investigation was immediately latched on to by her rival Trump, who immediately welcomed the announcement as a "big day".The controversial billionaire departed from his prepared speech at his rally in Manchester in New Hampshire. "I need to open with a very critical breaking news announcement," he told his cheering supporters, who waited for him for hours."FBI has just sent a letter to the Congress that they have found new emails pertaining to the former Secretary of State Hillary Clinton's email investigation. And they are reopening the case into her illegal and criminal conduct that threatened the national security of the United States," he said."This is a big day," he said alleging that the email scandal is bigger than the 'Watergate'. "Hillary Clinton's corruption is on a scale that we have never seen before. We must not let her take her criminal scheme into the Oval Office.""I have great respect for the fact that the FBI and the Department of Justice are now willing to have the courage to right the horrible mistake that they made. This was a grave miscarriage of justice that the American people fully understand," Trump said and hoped it would now be corrected.