Heeding his own call to welcome those displaced with open arms, Pope Francis has revealed that two Syrian refugee families have been found and housed in the Vatican itself - and will remain there "until the Lord wants."

The pontiff made the revelation during an interview with Vatican journalist Aura Miguel of Portugal's Radio Renascença just ahead of his visit to Cuba and the United States.

"Yes, yes, yes, they are already there," the pope said of the two families now living in the Vatican. "And Cardinal Comastri did this, my Vicar General for the Vatican, with him the head of the Almonry, who is Bishop Konrad Krajewski, who works with the people, with the homeless. It's he who made the showers under the colonnade, the barber's service. It's truly wonderful, that he brings people from the street to see the Museums and the Sistine Chapel."

When asked how long the families will stay, the pontiff responded, "Until the Lord wants. No one knows this, how it's going to end, no?"

Since March 2011 when the Syrian conflict began, over 4 million people have fled their war-torn country, and have been hoping to be relocated to Europe and other Western states. According to an official UN report, more than 220,000 lives have been lost and over 12.2 million people "continue to require life-saving aid."

Pope Francis, himself the son of immigrants, has issued a call to Europe to welcome more migrants. He has urged every parish, every religious institution and every monastery welcome a family and suggested that near-empty convents could even be used to house refugee families.

"A family gives more assurance of stability, a little to avoid infiltrations of another type," he said.

"When I speak of a parish welcoming a family, I'm not saying they're going to live at the rectory, at the parish residence, but that the parish community sees to it there is a place, a corner of a school to make a small apartment or, in the worst case, rent a modest apartment for the family, but that they have a roof, to be welcomed, and that they are integrated into the community. And there were many reactions. Many, many, right? There are convents that are almost empty."

The pontiff has acknowledged, however, that ISIS terrorists could sneak into Europe and even attack the Vatican by blending in with refugees seeking asylum.

"The truth is that just [250 miles] from Sicily there is an incredibly cruel terrorist group. So there is a danger of infiltration, this is true," Francis told Radio Renascenca. "Nobody said Rome would be immune to this threat. But you can take precautions," he stated. 

Despite such concerns, the Pope warned that Europe's refugee crisis is just the "tip of the iceberg," sparked by an "unjust" global economic system forcing hundreds of thousands of people to flee war and poverty in search of better lives.

"We see these refugees, these poor people who are escaping from war, escaping from hunger, but that's the tip of the iceberg," he said. "But underlying that is the cause, and the cause is a socio-economic system that is bad, unjust, because within an economic system, within everything, within the world, speaking of the ecological problem, within the socio-economic society, in politics, the person always has to be the centre.

"And today's dominant economic system has removed the person from the centre, and at the centre is the god of money. It's the fashionable god today. I mean, there are statistics."