The Chinese embassy in Manila called for a thorough investigation of an alleged bomb plot, protesting at the Philippine government's "soft attitude" towards a potential threat to Chinese citizens.
Agents of the National Bureau of Investigation (NBI) arrested the plot's alleged mastermind, lawyer Ely Pamatong, at Manila's airport late on Wednesday as he arrived from the southern city of Cagayan de Oro. He was reportedly set to fly on to Palawan, where he said he would hire a boat and "invade" the disputed Spratly - or Nansha - Islands.
Pamatong, a two-time presidential candidate and lawyer for the Muslim separatist group Moro National Liberation Front (MNLF), was arrested on the strength of a 2013 warrant charging him with malicious mischief for scattering hundreds of steel spikes on Manila's streets in 2004.
Upon his arrest, Pamatong told GMA news: "To a certain extent, I am responsible because I encouraged Jojo [Grandeur Guerrero]. My instruction [to him] was to do everything reasonable to stop Chinese economic domination of the Philippines, and dismemberment of the Philippines."
Guerrero and two others were arrested on Monday as they were about to place an improvised incendiary device in a car park toilet at the Manila airport.
National Security Adviser Cesar Garcia described Pamatong, who is in his 70s, as "delusional" and called his group "harmless".
In 2011, Pamatong, speaking as the leader of what he called the Discovery Crusade of the Philippines, declared war on China and called on Filipinos to kidnap Chinese living in the country.
An NBI official yesterday said that while Pamatong has long had warrants out for his arrest, authorities had refrained from detaining him because "he likes being arrested in order to call attention to himself".
"But this time, this is no longer a joke," the official said.
This week, as the self-proclaimed head of the United States Armed Freedom Fighters of the East, Pamatong allegedly ordered three followers to plant bombs at the airport and a nearby mall to show outrage against China. The NBI said the men also intended to strafe the Chinese embassy with gunfire.
A Chinese embassy statement said: "We hope and believe the Philippine side will take effective measures to ensure the security of the Chinese Embassy and its staff as well as all Chinese nationals residing in the Philippines."
Department of Foreign Affairs spokesman Charles Jose said the Chinese embassy was informed because "we need to assure them that this is not an official government policy and that we do not use violence as a means of resolving the disputes".
Military authorities dismissed the group as "comic relief", belittling its abilities. The "bombs" consisted of large firecrackers and timing devices crudely taped to plastic bottles of petrol.
Security forces based in Cagayan de Oro said Pamatong was in the city in the last two weeks recruiting for the MNLF.
Armed Forces Chief of Staff General Gregorio Catapang added: "Pamatong has been notorious for doing these things, so he's part of our continuous monitoring."
In 2004, Pamatong claimed responsibility for scattering some 800 steel spikes on Manila's roads, damaging a hundred cars. He was arrested in a vehicle that contained an assault rifle, a machine pistol, a grenade launcher, two automatic pistols, two binoculars, a sniper scope, a military compass, ammunition and a fake American passport. Despite all these, he was given bail.
A Muslim convert, he once sued Pope Benedict for "alleged disturbance of public order, swindling and teaching immoral doctrines".