Pope Benedict XVI has started a state visit to his native Germany, where he will lead a packed political and religious programme in the face of clamour for change from protesters.

Benedict is to visit Berlin, Erfurt in the former East Germany and the strongly Catholic Freiburg on his four-day trip, during which the 84-year-old Pope has 24 meetings scheduled and will give 18 speeches and sermons.

It is the pontiff's third visit to Germany following the World Youth Day celebrations in Cologne in 2005, which took place shortly after his election, and a trip to his native Bavaria in 2006.

In a political, social and religious speech to Germany's parliament later today, the Pope will address Germans and Europeans on the roots of Christianity and the importance of rejecting an intellectual vision of God.

While polls have shown that many Germans are indifferent to his visit, his parliament speech is likely to be met by protests from those calling for Catholic Church reforms and some lawmakers will be boycotting the event.

Victims of sexual abuse by clergy are believed to be planning to attend the protests, and the Vatican has refused to rule out the possibility that the pope will meet with some of them in person during his trip.

Tomorrow, after meeting with Muslims in Berlin, the Pope is expected in Erfurt for a highly symbolic trip to an Augustinian convent where a young Martin Luther prepared for priesthood in 1505.

After meeting with the Central Committee of Catholics, a powerful lay organisation, as well as young pilgrims and seminarians in Freiburg, the trip will end with a large open-air mass on Sunday.