The supreme head of the Roman Catholic church; Pope Francis on Sunday expressed pain and sadness at the deaths and suffering of migrants who tried to cross the English Channel, at the border between Poland and Belarus, and in the Mediterranean Sea.

Pope Francis appealed for authorities to “respect the humanity” of migrants and strive to help them after Britain and France traded barbs over the deaths of 27 migrants as they tried to cross the Channel.

Francis dedicated nearly all of his Sunday message to the defense of migrants, telling several thousand people in St. Peter’s Square that he felt pain over recent tragedies. The pope asked the faithful gathered in St. Peter’s Square for the traditional Sunday blessing to pray “for migrants and their suffering.”

“Let us think of how many migrants are exposed in these very days to very grave dangers and how many lose their lives on our borders,” he said.

“I feel pain when I hear news of the situation in which so many find themselves, those who died in the Channel, those at the border of Belarus, many of whom are children, those who drown in the Mediterranean. How much sorrow, thinking of them,” he said.

The deaths of 27 migrants on the English Channel shocked both Britain and France. Still, shipwrecks of that scale are not uncommon further south in the Mediterranean Sea as migrants flee poverty, natural disasters, and authoritarian regimes for a better life in Europe.

Francis raised his voice when he said “children”.

After the drownings in the Channel, French President Emmanuel Macron told Britain it needed to “get serious” or remain locked out of discussions over how to curb the flow of migrants escaping war and poverty.

France later canceled an invitation to British Home Secretary Priti Patel to attend a meeting on the issue on Sunday in Calais.

“I renew my heartfelt appeal to those who can contribute to the resolution of these problems, particularly civilian and military authorities, so that understanding and dialogue finally prevail over every type of exploitation and so that they direct their wills and efforts toward solutions that respect the humanity of these people,” the Pope said.

Francis, who has made the defense of migrants and refugees a cornerstone of his papacy, condemned traffickers. Migrants that had been returned to North Africa, he said, were reduced to slavery, with women sold and men tortured.