The revelation underscores the widening scope of the U.S. criminal inquiry into cyber attacks on Democratic Party organizations, including the presidential campaign of its candidate, former U.S. Secretary of State Hillary Clinton.
U.S. officials have said they believe those attacks were orchestrated by hackers backed by the Russian government, possibly to disrupt the Nov. 8 election in which Clinton faces Republican Party candidate Donald Trump. Russia has dismissed allegations it was involved in cyber attacks on the organizations.
The more recent attempted phone hacking also appears to have been conducted by Russian-backed hackers, two people with knowledge of the situation said.
Federal Bureau of Investigation representatives had no immediate comment, and a Clinton campaign spokesman said they were unaware of the suspected phone hacking.
