Downing Street has rejected claims in a Sunday newspaper that Gordon Brown mistreated staff and was investigated over the issue by a top civil servant.
The PM's spokesman said the Observer's claim a probe was ordered by Cabinet Secretary Sir Gus O'Donnell was "without foundation" and "malicious".
Mr Brown admitted he could get angry, but denied he has ever been violent.
At a rally on Saturday, he unveiled Labour's election campaign slogan "A Future Fair For All".
Claims of staff being intimidated by outbursts from Mr Brown are made in extracts from a new book by the Observer's chief political commentator Andrew Rawnsley.
Earlier reports had suggested the prime minister would be accused of hitting staff, but no such allegation was made in the extracts published on Sunday.
The PM's official spokesman said: "These malicious allegations are totally without foundation and have never been put to No 10."