Italian prosecutors have launched an inquiry into claims that the government of ex-Prime Minister Silvio Berlusconi tried to rig April's general elections.
Mr Berlusconi's coalition lost by a wafer-thin margin
The allegation is made in a documentary entitled Kill Democracy being given out on Friday with a left-wing magazine.
The authors say blank ballots were fraudulently counted in favour of Mr Berlusconi's centre-right coalition.
Former Interior Minister Giuseppe Pisanu, who oversaw the vote, said the claims were "false and libellous".
Mr Pisanu said he welcomed the investigation "because it will surely serve to erase even the remotest of doubts".
The official election results gave a razor-thin majority to the centre-left, while opinion and exit polls had suggested Mr Berlusconi's party would be soundly beaten.
The authors of the documentary are Beppe Cremagnani, a TV journalist, and Enrico Deaglio, editor of Diario, the magazine distributing it on DVD.
They point to a number of allegedly suspicious data, including a sharp drop in the number of blank ballots.
The film notes that every election in the past 60 years has seen about 1.5 million blank votes, while there were fewer than 500,000 in April's election.
The authors suggest that a computer program allowed the interior ministry to change blank votes.
Mr Berlusconi's Forza Italia colleagues have denied any wrongdoing and say they are considering legal action against the magazine.