The Holy Father and the 'R' word

But there is little sympathy for the Muslim minority inside Buddhist-majority Myanmar, where they are denied citizenship and not even identified as Rohingya.

They are instead labelled "Bengalis" -- shorthand for illegal immigrants from Bangladesh.

The big question is whether the Pope will address the group's plight head-on by using the 'R' word in front of a touchy Buddhist public.

Who are the Rohingya?

The Rohingya Muslim minority are based in Myanmar's western state of Rakhine.

They numbered around 1.1 million until the current crisis sent nearly two-thirds of them fleeing into Bangladesh.

Considered among the world's most persecuted peoples, they have been systematically stripped of their rights in Myanmar and coralled into an apartheid-like existence, with severe restrictions on movement and on access to basic services.

Officials and many members of the Buddhist public reject the existence of a Rohingya ethnicity, instead labelling the group as immigrants from Bangladesh despite the fact that many have lived in Myanmar for generations.

Bouts of communal violence have hit Rakhine since 2012.

But the worst violence erupted in late August after Rohingya militants staged deadly attacks on police posts.

The raids backfired, inviting an army reprisal so brutal that it emptied northern Rakhine of much of its Rohingya population, who told of mass rape, murder and arson.

Both the UN and US have accused the army of ethnic cleansing -- a charge the military steadfastly denies.

What has the Pope said about the Rohingya?

Pope Francis has taken a close interest in the group's plight, speaking about them on at least three separate occasions this year.

In February 2017 he called them "brothers and sisters" being tortured and killed for their faith.

He described the Rohingya as good and peaceful people who had suffered for years and urged Catholics to pray for them.

He again highlighted their suffering after the crackdown in August. Last month he mourned the plight of some "two hundred thousand Rohingya children in refugee camps" in Bangladesh.

"They have barely enough to eat, though they have a right to food. (They are) Malnourished, without medicine," he said.

Will he say the 'R word'?

Nobody knows how the canny, outspoken and unconventional Pope will handle the issue.

Catholic leaders in Myanmar have warned Francis against using the word "Rohingya" during his trip, fearing the country's small Christian minority could become the target of Buddhist hardliners.

Vatican officials have indicated that he has taken the advice seriously.

But he is renowned for his passionate appeals on behalf of the downtrodden. Any failure to mention the Rohingya by name may be seen as a disappointing concession.

The pontiff could adopt the preferred wording of civilian leader Aung San Suu Kyi, who refers to the Rohingya only as "Muslims in Rakhine state" -- though that middle path has invited fire from both sides of the conflict.

The 80-year-old pope's packed schedule will include many opportunities to weigh in on the crisis.

He will conduct two masses, hold discussions with the Buddhist clergy and sit down with Suu Kyi and army chief Min Aung Hlaing -- the man whose troops stand accused of crimes against humanity.

When he goes on to Bangladesh Francis may choose a diplomatic path and drop the "R-word". He made last-minute plans to meet a small group of Rohingya in Dhaka.

Why is it such a big issue?

Myanmar does not want its Rohingya, and support for them enrages Buddhist nationalists.

The global outcry at their treatment has stirred a chippy, defensive response among swathes of the public.

That largely plays out through social media invective but anti-Muslim violence has hit the country before.

The Buddhist-majority public has been weaned on a narrative of the Rohingya as Bengali interlopers, a narrative embellished by hardliners in the clergy and the army.

Some Buddhist nationalists accuse the Pope of meddling in a conflict he does not understand and may even inflame.

Observers fear more violence may put the country's fragile democratic gains in peril.