ROME — At least 20,000 Islamic demonstrators waving Turkish flags and chanting staged a defiant rally in Istanbul yesterday to protest against the pope’s arrival tomorrow.

The pope is set to defy death threats and security fears to visit Ankara, Ephesus, and Istanbul on a four-day trip to Turkey intended to bring the Catholic and Orthodox churches closer together.

But many Muslims are still angry at the pope’s address at Regensberg University in September. He quoted a 14th-century Byzantine emperor who claimed Muslims were “evil and inhumane.”

The Turkish Saadet political party, which is not represented in Parliament having only polled 1.2% of the vote in the 2002 elections, organized the rally.

Although Saadet claimed 1 million people would take to the streets and laid on 2,000 coaches, the numbers were far smaller. A crowd of mostly young Islamists and Turkish nationalists waved banners against the “sly” pope and demanded an end to the “Crusader Alliance.”

The protest may not have been huge, but there remain perils ahead in a country where Al Qaeda has struck with devastating effect and passions among the nation’s furious Islamic population are running high.

The pope used his address yesterday at the Vatican to call for calm. “I want to express my sentiments of esteem and sincere friendship,” he said. In a nod to the perilous security of the trip, the pope added: “I invoke the celestial protection of John XXIII, who was the apostolic delegate in Turkey for 10 years and nurtured affection and estimation for that nation. I ask you all to accompany me in prayer that this pilgrimage can bring all the fruits which God desires.”

The Vatican announced the pope would “follow in the footsteps of John Paul II” and visit the Blue Mosque in Istanbul. Benedict will be the second pope in history enter a mosque, after John Paul II’s visit to Damascus in 2001.

Turkish security forces have been put on high alert for the trip. Cardinal Walter Kaspar, who is a close friend of the pope, will be given his own security team after reports he has become a secondary target.

Another protest from the Grey Wolves, an ultra-nationalist movement, is expected when the pope reaches Istanbul. Around 40 of the group were expelled from Haghia Sofia last week with tear gas and arrested for their protest. Cardinal Tarcisio Bertone, the Vatican’s secretary of state, played down the security concerns yesterday, saying: “We have had almost daily information on the situation. There is no fear.”

However, he said that the trip will not win over many Turks. “Maybe they will not fill the streets, as happened in the visit of John Paul II. But we hope they will be watching their televisions and listening to the messages.”

The Vatican has also been trying to smooth the political tension with the Turkish government, which is furious the pope granted a personal visit in Rome to the Greek Cypriot president Tassos Papadopoulos a few weeks ago.

Yesterday, a spokesman for the Vatican insisted the Catholic Church “is not against Turkey joining the European Union.” He added: “The Vatican is not a member of the E.U. and does not take positions on these political arguments. If Turkey meets the criteria why should it not enter?” Two years ago, before his election as pope, Joseph Ratzinger said he did not wish Turkey to be admitted.

There was also an about-turn by Prime Minister Erdogan of Turkey who had previously chosen to snub the pope and attend a NATO summit in Riga.