The pope did not formally attend the summit, organised by the Sant'Egidio community, but met and lunched with the delegates as part of a pastoral visit to this impoverished southern Italian city.
"With respect for the differences between the various religions, we are all called to work for peace and... reconciliation among peoples," he said.
Orthodox Patriarch Bartholomew I, Archbishop of Canterbury Rowan Williams, Israel's chief rabbi Yona Metzger and the imam of the United Arab Emirates, Ibrahim Ezzedin, were among those attending the summit.
"Civilisations don't dialogue directly, but through those who carry their traditions and cultural values. So we should not speak of a dialogue of civilisations, but a culture of dialogue," Bartholomew told the opening.
In a similar vein, Metzger proposed a "United Nations of Religions" that would "embrace the heads of religious communities that have a profound influence on their congregations".
"If we sit down together around one table... surely we could arrive at effective solutions," he said.
Ezzedin, too, advocated a formal structure linking world religions, saying: "This important grouping of God-fearing people cannot and should not limit itself to processions, conferences and seminars."
"We need to form a permanent and authorised executive machinery for... executing any decisions we may make," he added.
The Muslim leader however spoke harshly of "unjustified provocations in places such as Iraq and Afghanistan and ... unfair dealings in Palestine" that have prompted "some Muslim individuals and groups (to go) astray and wrong themselves by violent actions."
He added: "We are dismayed by the behaviour of some great powers who continue to act aggressively against other countries, by means of military occupation under fabricated pretexts... forced regime changes and blunt interference in other countries' affairs."
The Sant'Egidio summits are meant to carry on the "spirit of Assisi" and were launched 21 years ago by John Paul II in the birthplace of Saint Francis.
The first summit, dubbed a World Day of Prayer for Peace, was attended by the Dalai Lama, Mother Teresa and other religious leaders.
The pope, then Cardinal Joseph Ratzinger, stayed away, reportedly out of concern that it put all religions on an equal footing.
Thus the timing of his pastoral visit to Naples has been billed as a "happy coincidence" by Sant'Egidio, a lay Catholic organisation that has mediated in several world conflicts.
The theme of this year's peace summit is "A World Without Violence: Faiths and Cultures in Dialogue," with topics to include AIDS, immigration, the plight of Africa and the quest for peace in the Middle East.
Earlier Sunday, Benedict celebrated an open-air mass as rain fell on pilgrims huddled under umbrellas in Naples' main square.
Lamenting "the sad phenomenon of violence" in the impoverished city, the pontiff said: "It's not only a matter of the deplorable number of crimes of the Camorra (mafia), but also the fact that violence tends unfortunately to become a widespread mentality, insinuating itself into the fabric of society."
Copyright © AFP 2007