European Commission President Romano Prodi escaped unhurt after a parcel bomb attack on his home in Bologna, northern Italy.
Mr Prodi was able to joke after the attack
Mr Prodi said a wrapped novel burst into flames as he opened it.
Two other explosions in rubbish bins near Mr Prodi's home in the past week were claimed by an anarchist group.
Mr Prodi said those attacks, which also failed to cause injury, and other warnings had made him more cautious as he tackled a pile of Christmas post.
"I kept it fairly far away. There was a big flame but without an explosion. It burned a piece of furniture and the carpet a bit," he said.
The pages of the book, wrapped in yellow paper and addressed to his wife, had been cut to insert explosive powder, Mr Prodi told reporters.
The book used was The Pleasure by Gabriele D'Annunzio, a famous early supporter of Fascism before his death in 1938. Mr Prodi joked that the choice of book might have been ironic.
An investigation was launched into who may have been responsible for the letter bomb.
The previously unknown group, Informal Anarchic Federation, claimed the earlier rubbish bin attacks in a letter to an Italian newspaper in which it said it wanted to target "the apparatus of control that is repressive and leading the democratic show that is the new European order".
Mr Prodi, who was in Bologna for the Christmas holidays, received messages of support from senior politicians including Italian President Carlo Azeglio Ciampi, the country's Prime Minister Silvio Berlusconi and French President Jacques Chirac also sent support.
His spell as president of the European Commission ends next year.
A former Italian prime minister, Mr Prodi is expected to return to Rome to take charge of Italy's centre-left coalition and challenge Mr Berlusconi in the country's next general election.