Last Sunday, two bombs tore through a Catholic cathedral in Jolo, on a southern Philippines island where Muslim militants are active. At least 20 were killed and 111 wounded.
Philippines Interior Minister Eduardo Manahan Año said he was convinced that Indonesian citizens committed suicide bombings at the church that, based on witness accounts and information from undisclosed sources.
"They are Indonesians," Ano, a former military chief, told CNN Philippines, as reported by AFP. "I am certain that they are Indonesians."
But analysts have raised doubts over these claims, citing a lack of evidence, and the Indonesian government has asked that the Philippines exercise restraint in blaming Indonesian citizens until the evidence is clear.
Sidney Jones, the director of the Jakarta-based Institute for Policy Analysis of Conflict (IPAC), said that Manila was apparently still in the dark as to the identity of the bombing perpetrators.
"There's no evidence! Different officials are saying different things - Malaysians, Yemenis, Indonesians. They actually have no clue," Jones told the Jakarta Post on Saturday.
Wiranto, Indonesia's Coordinating Minister for Politics, Law and Security, said that the Indonesian government could not yet confirm reports regarding the involvement of an Indonesian couple in the bombings.
Wiranto called on the Philippines not to state that the perpetrators were Indonesian citizens before obtaining certainty.
"Right now there are quite a lot of accusations from the Philippines, especially the Interior Minister, that there is involvement of Indonesian citizens in that [bombing] in the Philippines. Here I say that it is one-sided news," Wiranto said on Monday.
Wiranto said that Indonesia and the Philippines were still coordinating on the case.
"Until now the coordination has not been completed, and responsibility remains with the Philippine authorities themselves - the police, the parties concerned in the matters. On the other hand the coordination itself is still exploring who the perpetrator is."
It was reported on Monday that a senior Abu Sayyaf operative and four members of the militant group believed to be behind the deadly bombing surrendered to authorities over the weekend. Abu Sayyaf is a militant organisation operating within the Philippines, notorious for kidnappings and extremist factions and has pledged allegiance to Islamic State.
However, national police chief Oscar Albayalde said that the investigation into the church bombing in Sulu, a known stronghold of the Abu Sayyaf group, is “far from over”.
