Trump encourages Russia to hack emails of Clinton

Donald Trump sensationally challenged Russia on Wednesday to hack into Hillary Clinton's emails as a furious Democratic campaign accused the Republican nominee of inviting foreign spies to meddle in the US presidential election.

At a news conference, the New York billionaire tried to undermine his White House rival and promised a heyday of US-Russian relations under a Trump presidency.

Attacking Clinton as she prepares to accept her party's formal nomination, Trump turned his guns on the email scandal dating back to her time as secretary of state and more than 30,000 emails deleted on grounds of being personal and not related to her job.

"Russia, if you're listening, I hope you're able to find the 30,000 emails that are missing. I think you will probably be rewarded mightily by our press," Trump said.

The Clinton camp responded immediately and furiously.

"This has to be the first time that a major presidential candidate has actively encouraged a foreign power to conduct espionage against his political opponent," Clinton's senior policy adviser Jake Sullivan said.

'Extremely careless'

While the FBI declined to recommend charges against Clinton over the email scandal, its conclusion that she was "extremely careless" with classified information has seen the Democrat lose her polling advantage to Trump.

The row spotlights deep US distrust of Russia, fueling yet another day of headlines about whether Russian agents may have hacked into Democratic Party emails which, once leaked, hugely embarrassed the Clinton campaign.

Those emails leaked by WikiLeaks showed the extent to which party leaders sought to undermine Clinton's rival Bernie Sanders, even questioning his religious faith, and forced the Democratic National Committee chairwoman to resign.

The Kremlin denies interfering in the US election.

"Russia has never interfered and does not interfere in internal affairs, especially in the electoral processes of other countries," Kremlin spokesman Dmitry Peskov told reporters on Wednesday.