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Foreign hackers snooping on US presidential candidates: spy chief

Foreign hackers appear to have spied on the U.S. presidential candidates, the nation's top intelligence official warned Wednesday.

Foreign hackers appear to have spied on the U.S. presidential candidates, the nation's top intelligence official warned Wednesday.

And the FBI and Homeland Security are working with the campaigns to tighten security and prevent the cyber intruders from penetrating their defenses, Director of National Intelligence James Clapper said.

Clapper warned that there are likely to be more cyber attacks as Hillary Clinton and Bernie Sanders battle for the Democratic nomination and Donald Trump tries to rally Republican support for his candidacy.

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"We have already had some indications of that and a combination of DHS, FBI are doing what they can to educate both candidates of potential cyber threats," Clapper said, without specifying which candidates they were advising. "I anticipate as the campaigns intensify we will probably have more of it.

Foreign hacking against American political candidates is not new. There was evidence of it happening during the the 2008 presidential election won by President Obama, Clapper said.

NBC News reported in 2013 that prior to the 2008 presidential election, Chinese cyber spies had targeted the presidential campaigns of then Sen. Obama and Sen. John McCain in order to read emails and policy papers.

The hackers successfully compromised some emails, including private correspondence from McCain, NBC reported.

Also, both Obama's and GOP candidate Mitt Romney's campaigns were hit by Chinese cyber-attacks during the 2012 election.

This article first appeared on NBCNews.com.