The Secret Service and NYPD have teamed up to ensure the Pope's safety when he visits New York in September

Pope Francis’ visit to New York next month will be a “tremendous challenge”, the head of the US Secret Service has said.

When Pope Francis arrives in September people are expected to flood the streets in an attempt to get a look at the pontiff – but that’s only part of the security headache.

Ensuring security for a world dignitary is always a logistical challenge, but the Pope is proving to be harder to look after than most – mainly due to his love of mingling with crowds. So much so the Security Service, Vatican Security and the New York Police Department (NYPD) are teaming up to ensure the Pope’s safety during his trip in September.

Director of the Secret Service Joseph Clancy travelled to Italy in June to meet Vatican Security and to prepare the Pope for the upcoming visit.

“I went out to Rome to see first hand how their detail works, protecting the Pope and what he likes to do and how he travels within the crowds,” said Clancy in an interview with ABC.

The Pope is expected to ride through the city in the popemobile, but security are anticipating him stopping for selfies and to speak to those gathered in the streets.

Clancy said this proves a “tremendous challenge” adding: “He loves to be out with the people.”

The Security Service has been observing the Pope during his South America trip to see how he interacts with the crowds so they can “adapt”.

NYPD police Commissioner William Bratton said: “I’m loading up on the Excedrin [headache tablet] already for that visit. No, it is literally changing day-to-day in terms of what he would like to do.”

Pope Francis will visit the US and Cuba from September 19 to 27. He is scheduled to visit New York for two days, making several stops at landmarks including the September 11 Memorial, on September 24 to 26. He is also scheduled to address the annual gathering of the United Nations General Assembly during his time in the city.