AMMAN (AFP) - Pope Francis arrived in Jordan on Saturday at the start of a Mideast tour aimed at boosting ties with Muslims and Jews, as well as easing an age-old rift within Christianity.

As he stepped onto the red carpet at Amman airport, his white robes flapping in the hot desert wind, he was greeted by officials and two children dressed in traditional costume who handed him a bouquet of irises, the national flower of Jordan.

The Vatican has billed Francis' first visit to the Middle East as a "pilgrimage of prayer," saying he will shun bulletproof vehicles in favour of open-top cars, despite security concerns.

Speaking to reporters on his plane, the 77-year-old pope said he felt like the Biblical prophet Daniel heading to the lions' den.

"I feel like Daniel, but now I know that the lions don't bite," he said, a reference to his visit to a region roiled by political and religious division.

As his white car drove through the streets towards the royal palace, well-wishers waved Jordanian and Vatican flags and held up banners welcoming him, under the watchful eye of security guards.

Hours before his arrival, Christians across Jordan were piling onto buses to head for a stadium in Amman where Francis will celebrate mass.

"We are already singing for him to become a saint," said 77-year-old Sister Rachel, highlighting his dedication to the downtrodden.

"This pope is special. He only wants to see the poor and the diseased. He is the protector of the helpless," she said.

Before the mass, Francis will meet King Abdullah II, then head to a site on the River Jordan in the evening where many believe Jesus was baptised by John.

There he will hear first-hand of the suffering of Syrian refugees, 600,000 of whom are living in Jordan, giving him opportunity to reiterate calls for an end to the three-year war.

He is also expected to touch on the forced migration of Christians from the Middle East.

"Because of the global popularity that Francis enjoys, if he comes to the Holy Land and says 'I have your back,' it may mean something to Christians," John Allen, Vatican expert for the Boston Globe, told AFP.

Although only 250,000 Jordanians identify themselves as Christian - in a Muslim country of seven million - Prime Minister Abdullah Nsur said the visit would show the kingdom as an oasis of peace in a turbulent region of "blood, wars and repression."

Ahead of the visit, which will also take him to the Palestinian territories and Israel, Israeli police moved to lessen the possibility of trouble by ordering 15 rightwing Jewish activists to keep away from places he will visit after a string of hate attacks on Christian sites.

"It will be a purely religious trip," the pope told pilgrims at his last general audience in St Peter's Square earlier this week.

Francis said the main reason for the three-day trip was a meeting in Jerusalem with the Orthodox Patriarch of Constantinople, Bartholomew I, and "to pray for peace in that land, which has suffered so much".

A historic joint Catholic-Orthodox prayer service with Bartholomew on Sunday in the Church of the Holy Sepulchre - venerated as the place of Jesus' crucifixion and resurrection - is seen by the Vatican as the highlight of the visit.

Francis has made the ideal of unity of the Christian church, one of the priorities of his papacy.

He will also meet Muslim and Jewish leaders in Jerusalem.

The Argentine pontiff has already set the tone for a trip rich in symbolism by inviting two old friends from Buenos Aires to join him, Rabbi Abraham Skorka and Muslim professor Omar Abboud.

Early on Sunday, the pope will make a short helicopter ride across the Jordan River to Bethlehem, the West Bank town where Jesus was born.

He will meet Palestinian president Mahmud Abbas before celebrating mass in Manger Square. Afterwards he will chat meet several Palestinian refugee families for lunch and meet with a group of children.

He will then fly to Tel Aviv airport where he will be formally welcomed by the Israeli president before heading to Jerusalem for the meeting with Bartholomew.

Early on Monday, the pope will meet the Grand Mufi of Jerusalem at the Al-Aqsa mosque compound, the third holiest site in Islam and the holiest place in Judaism.

He will then visit the Western Wall, the holiest site at which Jews can pray, before going to Israel's national cemetery and the Yad Vashem Holocaust museum.

After a meeting with Peres and talks with Prime Minister Benjamin Netanyahu, he will celebrate mass in the Cenacle, where Christians believe Jesus held the Last Supper.