The confirmation of the Nov 28-Dec 1 trip to the predominantly Muslim nation came in an advisory to journalists on accreditation and a separate announcement that he was making the trip at the invitation of President Ahmet Necdet Sezer.

The German Pope will spend four days in Turkey, making stops at the capital, Ankara, as well as Izmir, Ephesus, where legend says Christ's mother went after his death, and Istanbul.

The main purpose of the visit is to meet in Istanbul -- the former Constantinople -- with Ecumenical Patriarch Bartholomew, spiritual head of the world's Orthodox Christians.

But the issue of Christian unity -- although still the main topic of the trip -- has been largely overshadowed by the worldwide controversy that followed his September 12 lecture at Regensburg University in his native Germany.

In the lecture, he quoted 14th-century Byzantine Emperor Manuel II Palaeologus who spoke of the Prophet Mohammad's "command to spread by the sword the faith he preached".

The leader of more than one billion Catholics has several times expressed regret for the reaction to the speech but he has stopped short of the unequivocal apology wanted by some Muslims.

Since the speech, the Pope or Vatican officials have said at least a dozen times that it has been misunderstood.

Some of the strongest criticism of the speech came from Turkey, where Turkish nationalists and Islamic activists have pushed for the trip to be canceled.

Even before the controversy over his comments on Islam, the Pope was already viewed with suspicion in Turkey.

When he was still Cardinal Joseph Ratzinger and worked as the Vatican's top doctrinal official, the future Pope said he was against Turkey's bid to join the European Union.

Some have accused him of undoing decades of bridge-building with Muslims by his predecessor, Pope John Paul II.

Patriarch Bartholomew, spiritual head of the world's 220 million Orthodox faithful, has said the controversy over the Islam remarks meant Benedict would meet a cooler welcome in Muslim Turkey than he would have otherwise.

"There will certainly be nationalists and fanatical Muslims who will campaign against the visit until the last minute," Bartholomew told reporters in Istanbul last month.

In September, the Pope met ambassadors from predominantly Muslim countries, including Turkey and assured them that he was committed to dialogue with Islam.

Church sources have said the Vatican's annual message to the Islamic world to mark the end of the Muslim holy month of Ramadan due to be released on Friday, was rewritten to address the tensions that arose after the Pope's lecture. Reuters