Pope Francis held mass and made a plea for migrant workers to be paid fairly, as he visited the affluent city-state of Singapore Thursday on the last stop of his marathon Asia-Pacific tour.

The 87-year-old pontiff said "special attention" should be paid to "protecting the dignity of migrant workers", in an address to political leaders and dignitaries. 

"These workers contribute a great deal to society and should be guaranteed a fair wage," he said.

There are an estimated 170 million migrant workers around the world. Most live in the Americas, or Europe-Central Asia. 

Cheap labour has been instrumental in the rapid growth of gleaming metropolises such as Dubai, Doha and Singapore -- the fourth stop on the pope's Asia tour. 

About 300,000 low-wage migrant workers are estimated to work in the city-state. Many flock from South Asia and from the Philippines, which has a large and devout Catholic majority.

Advocates say they are often exploited and endure poor living conditions, including forced dormitory lock-downs during the Covid-19 pandemic.

"I'm so happy that the pope has chosen to speak on this topic," a 34-year-old Filipino domestic helper told AFP, asking not to be named because she did not have permission from her employer.

"Even if they don't raise my salary, I'm still happy to know that the pope himself is fighting and praying for us," she said.

The woman said she earned US$460 a month, in a nation where the median gross income is US$3,985, according to Ministry for Manpower statistics.

The pope did not refer to workers in Singapore explicitly. But his comments are likely to cause unease inside a government which denies widespread abuse and is fiercely protective of its image.

'Mosaic of ethnicities'

Still, the Argentine pope was otherwise glowing about his hosts, praising the "entrepreneurial spirit" and dynamism that built a "mass of ultra-modern skyscrapers that seem to rise from the sea". 

"Singapore is a mosaic of ethnicities, cultures and religions living together in harmony," he said, painting the population of almost six million as a shining light for the world.  

"I encourage you to continue to work in favor of the unity and fraternity of humanity and the common good of all peoples and all nations," he said.

About 30 percent of Singaporeans are Buddhist, 20 percent have no religion and the rest are a mix of Catholic, Protestant, Taoist and Hindu. 

'I'm going to cry'

Singapore is the last stop on the pope's 12-day, four-nation Asia-Pacific trip aimed at boosting the Catholic Church's standing in the world's most populous region. 

Francis has defied doubts about his health during a journey that has taken him from Jakarta's grand mosque to a remote jungle of Papua New Guinea.

Despite recently undergoing hernia surgery and dealing with a string of respiratory issues, he has carried out dozens of public engagements, energised congregations and repeatedly sat for hours in the brutal tropical heat.

In East Timor, he held a mass for 600,000 faithful -- almost half the nation's population.

Although the crowds were markedly smaller in Singapore, groups of enthusiasts still lined the streets trying to get a glimpse of the one they call the "Holy Father".

On Thursday evening an estimated 50,000 people attended a mass in the country's national stadium. 

"Francis has this special ability to connect with the people, to touch people," said 21-year-old attendee Eveena Job, who was born in India but lives in Singapore with her family. 

Others did not make it into the stadium, and instead sat outside, on benches and picnic blankets, watching mass on electronic devices or listening to the faint noise from inside the arena. 

Genevieve Kamali, a 53-year-old Fijian, missed out on tickets and so huddled with eight family members outside. But she was not too disappointed.

"The holy father is just a few meters away," she told AFP. "Faith is about not seeing but believing."