Former FBI Director James Comey will face charges brought by the US Department of Justice after he was indicted for a second time, multiple sources told the BBC's US partner CBS News.

The specific charges are not known, but the sources said they relate to an image Comey briefly shared on Instagram last year that showed seashells forming the numbers "86 47".

Comey has insisted he did not know what the numbers meant, but Trump and other administration officials have said the post was a threat against the 47th president. "Eighty-six" is a slang term used to mean "eject" or "remove."

The department first brought charges against Comey in September, accusing him of lying to Congress over press leaks.

A federal judge dismissed that case two months later, saying that the interim federal prosecutor who brought the charges was improperly appointed.