-Russian government hackers breached Democratic National Committee computers to obtain opposition research on Republican Donald Trump, say officials.

The DNC's computer network was infiltrated in a "serious" incident, said chairwoman Debbie Wasserman Schultz.

A cyber security firm has been hired to help, she said, to "kick out the intruders and secure our network".

Russia has denied any involvement in the hacking.

"I completely rule out a possibility that the [Russian] government or the government bodies have been involved in this," Dmitry Peskov, a Krelim spokesman, told Reuters in Moscow.

The hack was first reported by the Washington Post.

DNC officials said the hack did not expose personal or financial information but email and chat traffic had been stolen.

The group says the hackers, two separated "sophisticated adversaries", have now been expelled from the system, and the breach was first discovered in April...

http://www.bbc.com/news/world-us-canada-36533449