JAKARTA - Indonesian police are on high alert ahead of Idul Fitri this weekend, over concerns of possible terrorist attacks as millions of Muslims around the country mark the end of Ramadan.

This after the police recently rounded up 36 Indonesians linked to the Jemaah Ansharut Daulah (JAD) terror network, following the twin suicide bombings at a bus terminal in Kampung Melayu, East Jakarta, last month that killed three policemen.

Only a handful of the 36 were behind the Kampung Melayu bombing, National police chief Tito Kanarvian told reporters on Tuesday (June 20) after officiating an awards ceremony at the police headequarters in Jakarta. "But they all belong to JAD cells that were planning terror attacks."

General Tito also confirmed that all of the suspects were connected to Bahrun Naim, an Indonesian terrorist who had joined the Islamic State in Iraq and Syria (ISIS), and some were just about to leave for the Middle East to join ISIS when they were nabbed.

The police also managed to seize several mobile phones, laptops, a bag of chemicals as well as propaganda paraphernalia during the raids across Java.

Indonesia has been regularly hit by a series of attacks after four militants from the JAD, which had pledged allegiance to ISIS, laid siege on Jakarta on Jan 14, 2016. ISIS had claimed credit for that attack as well as the latest incident in Kampung Melayu.

A similar suicide bombing at a police station in Solo just a day before Idul Fitri on July 6 last year, has also raised fears that terrorists are also willing to strike during the holy month of Ramadan.

General Tito said he has ordered counter-terrorism unit Densus 88 to ensure that security is "super tight" and that they are prepared to conduct premptive strikes against militants planning attacks in the weeks ahead. "So we will act quickly if there is any indication (of a terrorist plot)," he told reporters.