Indonesian police over the weekend arrested two more members of a militant group that had planned to bomb government buildings and the Burmese embassy in Jakarta, having arrested the bomb maker earlier in the week, a police spokesman said on Sunday.
All the suspects belong to Jamaah Ansharut Daulah, a militant group that backs Islamic State, police spokesman Boy Rafli Amar said.
Earlier this week, police arrested 23-year-old Rio Priatna Wibawa at his home in Majalengka, West Java, with a large amount of bomb-making material that he planned to use in attacks next month.
Local media reported that the amount of explosives seized would have resulted in a blast twice as powerful as the bomb that killed 202 people in a Bali nightclub in 2002.
Wibawa, who studied agricultural science at university and was unemployed, was a self-taught bomb-maker who had planned to distribute explosives to several places across Indonesia, police spokesman Boy Rafli Amar said on Saturday.
On Saturday and Sunday, police arrested two accomplices, who were alleged to have donated money to buy explosive material and helped to set up a home bomb-making laboratory, Amar said.
Indonesia has suffered a string of Islamic State-linked attacks this year, the biggest of which was a gun and bomb assault in Jakarta that killed four people in January.
Authorities are concerned about a resurgence in radicalism and say there are hundreds of Islamic State sympathisers in Indonesia, home to the biggest Muslim population in the world.
Lately, anger has been mounting in the Muslim-majority nations in Southeast Asia, such as Indonesia and Malaysia, over a crackdown on Rohingya Muslims in Burma, leading to demonstrations in several cities, including Jakarta.