Republican Donald Trump appealed to Russia on Wednesday to uncover and release thousands of emails Hillary Clinton did not hand over to U.S. officials who investigated her use of a private email system when she was secretary of state.

Clinton, a Democrat who faces Trump in the Nov. 8 White House election, responded with a campaign statement accusing him of posing a possible national security threat by urging Russia to commit espionage and influence the vote.

"Russia, if you're listening, I hope you're able to find the 30,000 emails that are missing," Trump, the Republican presidential nominee, told reporters. Clinton has said the emails she did not turn over were private.