Pope Francis faces calls to take tougher action against abuse as he visits Ireland this weekend -- a country where multiple scandals have badly damaged the image of the Catholic Church.

The pontiff arrives on Saturday for his first visit to this former bastion of Catholicism, which was last visited by a pope in 1979 when Pope John Paul II spoke to a crowd of 1.5 million people.

A new generation has shed traditional mores and Ireland, which has a gay prime minister, has in recent years voted to legalise same-sex marriage and abortion -- both once unthinkable.

Fintan O'Toole, a columnist for the Irish Times, said the Catholic Church in Ireland was "in some ways beyond repair".

"He will be greeted with joy by the faithful, but few, even among them, will expect him to be able to fix an institution that has been shaken to its very foundations," he wrote.

The Vatican was rocked this month by a devastating US report into child sex abuse that accused more than 300 priests in the Pennsylvania of abusing more than 1,000 children since the 1950s.

The pope wrote a letter to the world's 1.3 billion Catholics vowing to prevent future "atrocities" but conceding no efforts "to repair the harm done will ever be sufficient".

'Mandatory reporting'

Ireland has grappled with its own history of abuse, with multiple probes finding Catholic Church leaders protected hundreds of predatory priests over decades.

Former Irish president Mary McAleese revealed this month she rebuffed Vatican attempts in 2003 to keep Church documents inaccessible to government investigators.

Prime Minister Leo Varadkar, a symbol of Ireland's social seachange, has said he will press Francis for full disclosure to the police of abuse allegations received by Church officials when the pair meet briefly in Dublin on Saturday.

"We've brought in mandatory reporting over the last year and that's not the case in other countries," he told Sky News on Friday.

"It's good practice and should be applied across the board by the Church all over the world, and they have the power to do that if they wish to do so."

The Argentine pontiff will be in Ireland to close the 2018 World Meeting of Families (WMOF) -- a global Catholic gathering that takes place every three years.

In a video message released on Tuesday, he said he was "excited at the thought of returning to Ireland".

Francis will tour Dublin on Saturday on his Popemobile before visiting a hostel for homeless families and giving a speech at Croke Park stadium.

The highlight of the visit will be an outdoor mass in the city's Phoenix Park on Sunday expected to draw 500,000 people -- a tenth of the population.

Priests and nuns from across Ireland have flocked to the capital, where merchandise -- from candles to dolls to t-shirts all bearing his image -- are on sale.

At the WMOF conference, Maria Purificacion Alba Diaz said she had come to Dublin from Spain with her family to "share our faith".

"We think it is really important to support the pope," she said.

'We cannot stay silent' 

Critics of the Church have also been preparing for Francis.

Victims of clergy abuse and their supporters will hold a "Stand for Truth" demonstration in Dublin during the Sunday mass.

"We cannot stay silent as the Vatican uses its power and pomp to forcefully deny the reality of the harm it has done," organisers wrote on Facebook, where nearly 3,000 people had signed up to attend.

In Tuam, a town in western Ireland, a silent vigil was planned in solidarity with victims of "mother and baby" homes -- institutions accused of being punishment hostels for unwed pregnant women.

The Irish government in 2015 launched a commission to investigate 18 such homes -- the last of which closed in 1996 -- after revelations that up to 800 infants may have died over several decades at one run by Catholic nuns in Tuam.

Accusations of wide-ranging abuse in Irish Catholic institutions in Ireland date back several decades.

"We have such a history of abuse and so many have had their lives destroyed," Marie Collins, a survivor of clerical abuse, told AFP.

"It is important that while he is here this issue is addressed face on and we get clear words as to what he's going to do and what is going to happen next."

The Vatican confirmed Francis will meet with victims but provided no details.