Indonesian police investigate four men deported from Singapore over terrorism

The Indonesian police are investigating four men who were recently deported from Singapore over allegations of supporting the Islamic State group.

Anton Bachrul Alam, a spokesman from the National Police, on Tuesday told reporters in Jakarta that the male quartet, who age between 15 to 49, were arrested in Singapore last weekend when they were allegedly en route to Syria where the IS is headquartered.

"We are now investigating them to find out more," Anton said, noting that the group are currently in the custody of the police's counterterrorism unit in Jakarta.

Reports said that the quartet are members of Jamaah Anshorut Daulah, which is one of three Indonesian radical groups supporting the IS.

The four are believed to be followers of Aman Abdurrahman, one of the most influential hardline clerics in Indonesia who is currently in jail for terrorism.

Aman, who is believed to have recruited hundreds of Indonesians to be the militants for the IS, met the four suspects from his religious boarding school in West Java.

The group had flown into Singapore from Soekarno-Hatta International Airport in Jakarta before traveling to Malaysia's Johor and spent three days there and then returning to Singapore, according to Indonesian media.

Singaporean officials arrested and deported them on Sunday.

Two of the suspects are reportedly brothers: 15-year-old Muhamad Mufid Murtadho and 23-year-old Mukhlis Khoirur Rofiq, who are from West Java.

Meanwhile, the others are Untung Sugema Mardjuk and Risno, and they were born in Jakarta and Central Java, respectively.

Indonesian officials estimated that some 500 Indonesians have joined IS to fight in Syria, and about 100 of them are thought to have returned home.