Pope Benedict XVI has canceled a visit to one of Rome's best-known universities, because protests threatened to overshadow the event.

Dozens of students and teachers at La Sapienza University say they condemn the pontiff's conservative stand on many scientific issues.  A total of 67 professors signed a letter calling the Pope a backward-thinking theologian who forces religion into science, and asked that he not be allowed to speak at the school.

It is rare for the pope to cancel such a visit, but in a brief statement Tuesday the Vatican said "it was considered opportune to skip the event."

Instead of giving a speech in person on Thursday as planned, the pope will send a copy of his talk to the university this week.

Some information for this report was provided by AFP, AP and Reuters.