Pope Francis denounced that extremists around the world are "perverting" religion to justify violence as he visited Albania on Sunday, holding up as a model the Balkan nation where Christians and Muslims endured brutal oppression under communism but now live and work peacefully together.

Security was unusually tight for Francis' 11-hour visit to the majority Muslim country amid reports that militants who trained in Iraq and Syria had returned and might pose a threat.

The Vatican insisted no special security measures were taken, but Francis' interactions with the crowd were much reduced compared to his previous foreign trips: His open-topped vehicle sped down Tirana's main boulevard, not stopping once for Francis to greet the faithful as is his norm.

He only kissed a few babies at the very end of the route as he neared the square where he celebrated Mass, and then left quickly when it was over. Uniformed Albanian police formed human chains to keep the crowds at bay behind barricades while Francis' own bodyguards stood watch, perched on the back of his car or jogging alongside. Albania's Interior Ministry promised "maximum" protection from 2,500 police forces and beefed-up patrols at border crossings.

In his opening speech, Francis told President Bujar Nishani, Albanian officials and the diplomatic corps that Albania's interreligious harmony was an "inspiring example" for the world, showing that Christian-Muslim coexistence was not only possible but beneficial for a country's development.

"This is especially the case in these times in which authentic religious spirit is being perverted by extremist groups," he said.

"Let no one consider themselves to be the `armor' of God while planning and carrying out acts of violence and oppression!" Francis said in the wood-paneled reception room of Tirana's presidential palace.

Albania's religious harmony was on hand during Francis' main event Sunday: A Mass in a square named after the country's most famous Catholic -- Mother Teresa -- attended by senior representatives of Albania's Muslim, Orthodox and Bektashi groups, seated in places of honor.

In all, the Vatican estimated that some 250,000-300,000 people had turned out for the Mass and to line up along his motorcade route.

It was Francis' first visit to a majority Muslim nation since the Islamic State announced its crackdown on Christians in Iraq, with members of religious minorities being killed, persecuted or forced to flee their homes by militants. The Vatican has voiced mounting concern about the exodus of faithful from lands where Christian communities have existed for 2,000 years.

Muslims make up about 59 percent of Albania's population, with Catholics amounting to 10 percent and Orthodox Christians just under that, according to the country's official figures.

The capital's main Boulevard Martyrs of the Nation was decorated with Albanian and Vatican flags, as well as giant portraits of 40 Catholic priests who were persecuted or executed under Stalinist dictator Enver Hoxha, who declared Albania the world's first atheist state in 1967. Hundreds of priests and imams were jailed and scores executed before the regime fell in 1990.

Francis paid tribute to these martyrs and those from other faiths, saying they showed witness to their faith even under persecution.

"Recalling the decades of atrocious suffering and harsh persecutions against Catholics, Orthodox and Muslims, we can say that Albania was a land of martyrs," he said in his homily.

Francis had a busy schedule in Tirana: In addition to the address to Albanian authorities and Mass, he was meeting with leaders of different faiths, celebrating a vespers service and visiting children cared for by charitable groups before returning to the Vatican Sunday night.

The Vatican spokesman, the Rev. Federico Lombardi, insisted that no special security measures were taken, and said Francis didn't stop to greet the crowd as usual because he didn't want to fall behind schedule.

On previous foreign trips, including his last one in South Korea, Francis frequently has run behind schedule because he spends so much time greeting crowds.

Albanian police said they had the security situation under control. Cell phone providers complied with a request from police to jam cellphone reception in the area where the pope was in downtown Tirana. People attending the pope's Mass were told to avoid wearing heavy clothing since they would be checked by police and not to bring bags, suitcases or glass bottles.

"There is no threat to the pope's security. We have undertaken all the measures and everything will go well," police chief Artan Didi told reporters after a meeting with Interior Minister Saimir Tahiri on final security arrangements.

Security at the Vatican itself has been beefed-up in recent days: More barricades and police were out in force during Francis' weekly general audience this past week and Italian media reported security was being doubled.

Francis' decision to visit tiny, poor Albania before any major European capital was in keeping with his desire for the Catholic Church to go to the "periphery." Albania is seeking European Union membership and his visit comes just a few weeks before he delivers a major speech to the European Parliament in Strasbourg, France.

Albania's president, Nishani, thanked Francis for making the country his first European destination, saying it was a historic event for all Albanians.

"There is no intolerance, extremism among us but reciprocal respect inherited from generation to generation," he said. "From an atheist country, we have turned into a country of religious freedom."