Pope Francis on Thursday used his first public remarks since arriving in New York to express solidarity with Muslims after a devastating stampede in Saudi Arabia.

"I want to express the closeness of the church in the face of the tragedy people suffered in Mecca," said the pontiff at the start of his homily during prayers at St Patrick's Cathedral.

The stampede killed at least 717 people and injured hundreds more at the hajj, one of the worst-ever tragedies at the annual Muslim pilgrimage.