Cardinal Pietro Parolin, the Vatican’s secretary of state, told reporters on Tuesday that the Pope had a number of concerns about the initiative and that he “will not participate” as a result.

“For us, there are... some critical issues that should be resolved,” he said. “One concern is that, at the international level, it should above all be the UN that manages these crisis situations. This is one of the points on which we have insisted.”

Pope Leo has repeatedly criticised Mr Trump’s policies since being named the first American pontiff. In October last year, he questioned whether (Trump's) hardline immigration policies were in step with the Catholic Church’s “pro-life” values.

“Someone who says I am against abortion but I am in agreement with the inhuman treatment of immigrants in the United States, I don’t know if that’s pro-life,” he told the media in Rome.