Donald Trump
Donald TrumpReuters

Leading Republican presidential candidate Donald Trump's campaign manager has been charged with assault, over an incident in which a journalist was violently manhandled at a campaign event.

Corey Lewandowski was charged Tuesday with simple battery over a confrontation with former Breitbart reporter Michelle Fields.

He plans to plead not guilty, the Trump campaign has confirmed.

Police have released new video footage from the event, which took place on March 8 in Florida, in which Lewandowski can be seen grabbing Fields roughly by the arm, in an encounter which left her bruised and shaken. Fields was attempting to ask Trump a question, when she was pulled away by his aide.

The controversy over the assault of a journalist was compounded when Fields later quit Breitbart, claiming the company had failed the back her and had essentially become a backer of the Trump campaign.

"Mr Lewandowksi is absolutely innocent of this charge," an official Trump campaign statement said. "He is completely confident that he will be exonerated."

Trump himself has also come out in defense of Lewandowski, claiming the video footage proves nothing.

The latest controversy comes as Trump prepares for a special CNN town hall meeting later Tuesday, and as polls show him facing a tough challenge from rival Ted Cruz in the upcoming Wisconsin primaries.