Turkish President Tayyip Erdogan flew to Italy on Sunday ahead of talks with Pope Francis that are expected to centre on Jerusalem after U.S. President Donald Trump recognised the holy city as the capital of Israel.
The pope and Erdogan previously met when Francis visited Turkey in 2014.
The two leaders later went for a closed-door meeting at the palace's Library Hall, which ended after one hour.
Aside from Erdoğan and his wife, the Turkish delegation included Foreign Minister Mevlüt Çavuşoğlu, Economy Minister Nihat Zeybekci and National Defense Minister Nurettin Canikli as well as EU Minister Ömer Çelik and Minister of Energy and Natural Resources Berat Albayrak.
The pope and the Turkish president also exchanged gifts. The pontiff, as well as a medallion with the dove of peace, donated Erdogan an etching of St Peter's as it was at the beginning of the 17th century, a copy of his encyclical Laudato si' and his message for this year's World Peace Day.
According to local media, the main topic of conversation will be the situation in Jerusalem, in addition to the fight against terrorism, the humanitarian crisis of refugees and the rise of racism and Islamophobia. Several also held signs calling for the release of Abdullah Öcalan, a Kurdish nationalist leader who has been jailed in Turkey since 1999. He reportedly cited the restoration overseen by the government of 14 churches and a synagogue in Turkey. Bilateral relations are good and Italy remains committed to continuing dialogue with Ankara, the sources said.
In a brief statement, the Holy See said Francis and Erdogan discussed the Middle East "with particular reference to the status of Jerusalem, highlighting the need to promote peace and stability in the region through dialogue and negotiation, with respect for human rights and worldwide law".More news: North Korea: SOTU speech 'the height of Trump-style arrogance'
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But the two men have found common ground over Jerusalem, speaking by phone after Trump made his announcement in December and agreeing that any change to the city's status should be avoided.
Erdogan is the first Turkish president to visit the Vatican in almost six decades. Italian Deputy Prime Minister Paolo Gentiloni will also be present.
"Following the violent aggression towards security forces by protesters at Castel Sant'Angelo, the demonstration was brought to an end", said the Rome police headquarters in a statement.
And at least two people were detained when protesters tried to break through cordons from an authorised protest nearby.
"I am surprised the pope is willing to meet with a person like that, a dictator, an assassin, with blood on his hands", Said Durson, who was among the demonstrators, said.
"In Afrin, a new crime against humanity is under way", the Kurdish association, which will stage a sit-in protest not far from the Vatican, said.