Terrorist groups are planning kidnappings on central Philippine islands that are popular with tourists, the US embassy has warned, fuelling concerns Islamic militants infamous for hostage taking are roaming wider.
A travel advisory from the US embassy in Manila on Thursday warned Americans to avoid the southern regions of Cebu island, one of the nation's most popular tourist sites because of its idyllic beaches, spectacular diving and whale watching.
"The U.S. Embassy alerts U.S. citizens that terrorist groups are planning to conduct kidnappings in areas frequented by foreigners on the southern portion of Cebu Island," the advisory said.
The embassy identified three locations -- Dalaguete and Santander on Cebu, and nearby Sumilon island. Those areas are a short boat ride to tourist hotspots Bohol and Dumaguete.
The warning came after a surge in kidnappings by Islamic militants in the southern Philippines, which included the first attack on a cargo ship in the high seas and the murders of foreigners after ransoms were not paid.
President Rodrigo Duterte's office released a statement on Friday confirming police had reported an unspecified kidnapping plan in southern Cebu and that security had been increased in the area.
The US embassy did not name who was planning the attacks, but the strife-torn south of the mainly Catholic Philippines is home to various militants groups that have in recent years sworn allegiance to the Islamic State group.
The most notorious is the Abu Sayyaf, a loose network of militants formed in the 1990s with seed money from Osama bin Laden's Al-Qaeda network, which has earned millions of dollars from kidnappings-for-ransom.
The Abu Sayyaf is based on islands about 500 kilometres (300 miles) southwest of Cebu, and most often kidnap people from coastal regions and vessels close to their strongholds of Jolo and Basilan islands.
However the militants kidnapped two Canadians, a Norwegian and a Filipina from Samal, a tourist island about 500 kilometres to the east of Jolo last year. The Canadians were beheaded and the other two were released after ransoms were reportedly paid.
The Abu Sayyaf has also been blamed for the abductions of dozens of Indonesian and Malaysian sailors in smaller vessels in the area.
Last month the captain of a South Korean cargo ship was abducted in waters off the southern Philippines, in the first such attack on a large merchant vessel.
Duterte has launched a military offensive to eradicate the Abu Sayyaf.
Another extremist group, the Maute gang, was blamed for a bombing in Duterte's home town in the southern city of Davao that left 15 people dead in September.