Manila: President Benigno Aquino urged the Philippine people on Monday to be alert against panic, stampedes or any attempts to sow chaos during this week`s visit by Pope Francis.
Aquino said the large number of people trying to see or get close to the pontiff could be a source of danger, even to Pope Francis himself.
He cited the millions expected to attend the mass which the pope will say in Manila`s central park on Sunday.
"There is no doubt that in a large gathering like this, there is a possibility of chaos even without the threat of terrorism, and an even greater possibility if someone plans to cause chaos," Aquino said in a televised message.
"This shows the danger and the threat when so many participate in these events."
Citing previous attacks against Pope John Paul II and Pope Benedict, he urged the public not to impede Pope Francis`s convoy.
"If someone blocks the convoy by trying to get near the holy father and the convoy stops, what was a moving target becomes a stationary target," he said.
"I ask you, do you want history to record that a tragedy involving the pope happened in the Philippines?" he asked the population of the largely Catholic nation.
Aquino warned that even one person breaking the security cordon could trigger a stampede, saying "There might be some people who may want to get a `selfie` (with the pope)."
National police carried out a "dry run" to prepare for the pope`s arrival in the country on Thursday, his first visit to Asia`s bastion of Catholicism.
Security will be a major issue throughout the pontiff`s Asia trip, but Philippine Church officials have said he will not travel in a bulletproof "popemobile" because he wants to be closer to his flock.
Organisers say cellphone signals may be blocked and have called on the public not to bring backpacks to the mass.
Traffic enforcers will be equipped with adult diapers to ensure they do not leave their posts.
Although officials have said there is no reported terror threat against Pope Francis, they are on alert for any attempt to disrupt his visit.
In the past, the Philippines has been hit by numerous bomb attacks blamed on Muslim extremists, although these usually take place in the south.