Pope prays for people of tsunami-hit Tonga

"My thoughts go to the people of the islands of Tonga, hit in the past few days by the eruption of the underwater volcano, causing enormous material damage," Francis said.

"I am particularly close to the people who are being so sorely tried and I implore God to comfort them in their suffering. I invite everyone to join me in prayer for these brothers and sisters," he said.

Hundreds of homes in Tonga's smaller outer islands have been destroyed, with at least three deaths after Saturday's huge eruption triggered tsunami waves that rolled over the islands, causing what the government calls an unprecedented disaster.

With the nation's airport smothered by volcanic ash and communications badly hampered by the severing of an undersea cable, information on the scale of devastation has come mostly from reconnaissance aircraft.

Tonga, despite it small size, has a cardinal, Cardinal Soane Patita Paini Mafi, who was appointed in 2015.