Philippine security forces are on high alert to secure a Catholic religious procession today that draws millions to the capital Manila, after receiving reports that the gathering may be targeted by Muslim extremists.

"We have not monitored any clear and present danger, but it is always better to be prepared. We just want to be sure," said director-general Ronald de la Rosa, the police chief.

The day-long procession, known as the "Traslacion", sees about two million devotees scrambling to touch an image of a 200-year-old statue of a dark-skinned Jesus, known as the Black Nazarene.

Mr de la Rosa said yesterday that police had asked telecoms carriers to shut down cellphone signals in central Manila, as a security measure on top of signal jammers already installed in key locations.

Muslim militants with ties to the Islamic State in Iraq and Syria (ISIS) have used mobile phones to set off bombs in recent attacks.

A gun ban has been enforced across Manila. Police have also prohibited the use of backpacks and drones.

More than 5,700 policemen are being deployed to secure the procession route.

Assistant Communications Secretary Ana Maria Banaag said yesterday that President Rodrigo Duterte was "satisfied" with measures being laid down to secure the Black Nazarene procession.

Security officials are concerned that ISIS-linked terrorist groups in the war-torn southern island group of Mindanao may target the procession in retaliation for recent setbacks dealt by the government.

A police and military team yesterday killed a Pakistani, identified as Abu Naila, and his female companion, believed to be members of Ansar al-Khilafah Philippines.

Chief Superintendent Cedrick Train, a police regional director, said Abu Naila resisted arrest and attempted to throw a grenade at security forces conducting a manhunt for fighters of the militant group in Sarangani province.

Mr de la Rosa said security forces had effectively broken the backbone of Ansar al-Khilafah with the killing of its leader, Mohammad Jaafar Maguid, alias "Tokboy", last week.

Maguid was said to have been an apprentice in bomb-making of Malaysian terrorist Zulkifli Hir, alias "Marwan", who was killed by police commandos in his hideout in Mindanao in January 2015.

Security forces are also on alert for possible attacks from two other ISIS-linked groups, the Maute and Abu Sayyaf groups, which had seen their fighters either killed or arrested in military offensives meant to evict them from their strongholds.

At least 11 Maute militants were killed in a military operation in November last year, after the group tried to occupy government buildings in a remote town in Lanao del Sur province. Last month, Malay- sia's security forces killed the leader of an Abu Sayyaf squad snatching tourists, fishermen and sailors in waters off Sabah state and the Philippines' Sulu archipelago.

In a statement yesterday, the Philippine military guaranteed the security of those coming to the Black Nazarene procession.

"They should not be cowed by reports of possible terrorist attacks as that will fulfil the desires of terrorists. The faithful are assured that the security forces have prepared for and implemented the security measures...," it said.

"They should trust that their security forces are out there, among them, and looking over them in the entire period."