Sept 12 (Reuters) - U.S. authorities are preparing to

file criminal charges after the Trump campaign said in August

that some of its internal communications were hacked and blamed

the Iranian government, the Washington Post reported on

Thursday, citing people familiar with the matter.

The Iranian government has denied that it hacked the Trump

campaign.

An FBI investigation focused on an online persona called

"Robert," who shared documents they falsely claimed to have

taken while working with the Trump campaign, the Post said.