ISIS-linked terrorists are planning to kidnap foreigners in two of the Philippines most popular tourist spots, the US Embassy has warned.
The city of Puerto Princesa and the nearby underground river, both located on the island of Palawan and visited by thousands of tourists every day, were named as likely targets.
The warning was issued a month after an abduction and bombing plot by Abu Sayyaf, a group that has pledged allegiance to ISIS, was uncovered.
The US Embassy has warned tourists in the Philippines city of Puerto Princesa and the nearby underground river (pictured) that they are being targeted by terrorists in a kidnap plot
President Rodrigo Duterte has said security has been beefed up around the affected areas and officers are being told to shoot suspected militants on sight
Hardline President Rodrigo Duterte said security has been beefed up in the affected areas and officers have been told to shoot suspected militants on sight.
Following the US travel advisory, Canada and Britain also updated their own advice, but included additional warnings about Dumaguete, Siquijor and Cebu, in the central Philippines.
The Abu Sayyaf last month attempted a kidnapping raid on Bohol island, a popular tourist destination in the central Philippines, but were foiled after the military uncovered the plot.
Security forces found the militants a day after they arrived on speedboats at Bohol, which is 300 miles north of the terror group's bases.
A fierce gun battle followed in which nine militants, three soldiers and one policeman were killed, according to authorities.
Another militant subsequently died in police custody, officials said.
The Bohol raid occurred days after the US Embassy issued a warning of potential kidnappings there and the neighbouring island of Cebu, which has a major city of the same name.
The Abu Sayyaf regularly kidnaps foreigners and locals to extract ransom which it uses to fund its activities.
Its aim is to establish an independent Islamic state spanning several islands in the Philippines for the Moros minority people.
The militants typically raid coastal areas after sailing from their southern island strongholds on speedboats, although in recent years they have also attacked cargo and merchant ships.
After the US issued its travel advisory on Wednesday, Britain and Canada updated their own advice, but also included several islands in the central Philippines
They beheaded two Canadians last year and an elderly German sailor in February after demands for millions of dollars were unmet.
The Abu Sayyaf raided a resort in Puerto Princesa's Honda Bay in 2001, abducting three Americans and 17 Filipinos.
One of the Americans was beheaded, while one was killed in a military rescue attempt a year later. The third American was freed in the rescue effort.
The Abu Sayyaf has also kidnapped people from Malaysian coastal resorts, which are a short speedboat ride from its southern Philippine bases.
In recent years the kidnapping threat had largely been restricted to the southern Philippine region of Mindanao.
Until recently, foreign governments had not warned of kidnapping threats in the central and western Philippines.
Asked in Manila about the latest travel warnings for Palawan, Duterte said he wanted the suspects dead.
'My order to the security forces is shoot them on sight. Kill them,' Duterte said.
Duterte last year ordered a major military offensive to extinguish the Abu Sayyaf on their southern bases, but the militant threat continued to grow.
The Philippines is looking to conduct joint patrols with Indonesia and Malaysia to stop the rising number of kidnapping raids on cargo and merchant vessels near the Abu Sayyaf's bases.
Duterte on Wednesday repeated a warning that the Islamic State group was gaining influence in the Philippines.
'We have a problem with terrorism. What looms very big ahead is the IS. They are coming in,' Duterte said.