Farouk Arnaz – Pepi Fernando, the alleged mastermind, financier and bomb-maker behind the Good Friday bomb plot and book-bomb campaign, was a former member of the extremist Indonesian Islamic State (NII), a police source said on Sunday.

He was once a member of NII, but he quit," the source told the Jakarta Globe. "However, NII's idea of creating an Islamic state and implementing Shariah law in all aspects of daily life remained with him."

The source, who wished to remain anonymous, would not say why Pepi, 30, had left the group.

The police and the State Intelligence Agency (BIN) are currently investigating the radical group, which is reported to have a training camp in the restive southern Philippines and also has received support from a group headed by Malaysian-born militant Noordin Mohammad Top.

The source said they were investigating Pepi's links to Saefudin Zuhri and Mohammad Syahrir, who were both killed by police during raids in the aftermath of the twin hotel bombings in Jakarta in 2009. Zuhri and Syahrir both had NII links, he said.