MANILA — Militants detonated a car bomb at a military checkpoint on Tuesday in the southern Philippine island of Basilan, killing at least 10 people in a brazen attack that underscored the continuing insurgent threat in the southern part of the country.
The attack happened as troops flagged down a van at a roadblock heading into Lamitan City. When the driver failed to answer questions, he apparently detonated the explosive, the military said.
The blast instantly killed a soldier, three pro-government militiamen and several civilians, the military said. Nine others, including five soldiers, were injured.
Lt. Col. Mon Aldomovar, commander of the 3rd Scout Ranger Battalion in the area, said he suspected that the militant group Abu Sayyaf was behind the bombing.
“They are responsible for this incident,” he said of the group.
Founded in the 1990s as a separatist group, Abu Sayyaf has, in recent years, degenerated into a criminal organization specializing in bombings and kidnappings.
Over the last two years, the group has beheaded a German national and two Canadian hostages after their governments refused to negotiate ransom. The United States government has designated the group a terrorist organization.
One of its commanders, Isnilon Hapilon, has pledged allegiance to the Islamic State, and last year led hundreds of fighters from Southeast Asia and the Middle East in taking over Marawi, a city on the southern island of Mindanao. The takeover led to a five-month siege in which the group beheaded Christian residentsand engaged the military in the fierce street battles before Mr. Hapilon and other group leaders were killed.
Since then, the Philippine military has been on heightened alert in the South, setting up roadblocks like the one involved in Tuesday’s attack.
“Our troops were alerted when they saw a suspicious-looking driver,” Mr. Aldomovar said of the incident. “But when he was told to stop and when our troops were about to inspect the vehicle, it suddenly exploded.”
The military has received reports that Abu Sayyaf had been planning to infiltrate the area and carry out bombings.
Tuesday’s attack was the deadliest in the southern Philippines in recent months, and “is the first time we encountered an I.E.D. inside a four-wheeled vehicle,” Mr. Aldomovar said, referring to improvised explosive devices.
“We don’t know what was really the target,” he added. “It was prematurely detonated at our checkpoint when our personnel stopped the vehicle from going into the city.”
The attack happened four days after President Rodrigo Duterte invited the Sayyaf to the peace table, ignoring a long-held state policy of not negotiating with terrorist groups.
Mr. Duterte’s spokesman, Harry Roque, vowed “to bring the perpetrators of this brazen attack to justice.”