Pope Francis, the first leader of the world’s 1.3 billion Catholics to visit the Arabian Peninsula, will attend an interfaith meeting in the UAE on Monday as part of his outreach to Muslims.

The pope’s highly publicised 48-hour visit to the United Arab Emirates will also include an open-air mass on Tuesday for 135,000 of the Muslim country’s million Catholic residents, set to be the largest public gathering in the country’s history.

The pope was expected to raise the issue of Yemen, devastated by a war in which the UAE is a key player, in talks with Abu Dhabi’s Crown Prince Mohammed bin Zayed.

To mark the occasion, the pontiff offered the crown prince a framed medallion of the meeting between St. Francis Assisi the pope’s namesake and the Sultan of Egypt Malek al-Kamel, in 1219.Sheikh Mohammed, in turn, offered a deed for the plot of land on which the first church in the UAE was built.The emirate’s crown prince was also at the airport to greet the pontiff, who has made strengthening ties between Christianity and Islam a cornerstone of his papacy.

Yemen is the scene of what the UN calls the world’s worst humanitarian crisis, triggered by the intervention of Saudi Arabia, the UAE and their allies in a war between the government and Huthi rebels.

Pope Francis, who made history when he touched down in Abu Dhabi on Sunday night, said he came “as a brother, in order to write a page of dialogue together, and to travel paths of peace together”.

The UAE has dubbed 2019 its “year of tolerance”, but rights groups have criticised the country for its role in Yemen, where an estimated 10,000 people have been killed since the Saudi-led alliance including the UAE joined the government’s fight against the Huthis in 2015.

Rights groups, which have slammed the UAE over its intolerance of dissent, have also urged the pope to raise the issue of Ahmed Mansoor, an Emirati activist serving a 10-year prison term.

Before heading to the Gulf on Sunday, Pope Francis urged warring parties in Yemen to respect a truce agreement and allow deliveries of food aid.“The population is exhausted by the lengthy conflict and a great many children are suffering from hunger, but cannot access food depots,” he said.