A death threat against Premier Silvio Berlusconi bearing Muslim slogans was sent to the offices of Rome daily La Repubblica Friday.
The daily gave police the envelope, which contained a bullet.
The threat ended with the words, ''Allah is great''.
It was signed 'Azzam', a common Muslim name.
Other government members and the speakers of both houses of parliament were cited as possible targets.
Investigators said the letter appeared ''at first glance not very credible and rather generic''.
It was ''unlikely that the threats are to be attributed to specific subversive groups,'' they said.
But antiterrorism experts are examining the letter closely nonetheless.
They said they will compare it to other such threats.
