?The Indonesian counter-terrorism agency (BNPT) will pay close attention to over 50 militants who have returned home from joining the activities of global terrorist group, IS, in Mosul of Iraq, top official of the agency disclosed here on Friday.

Head of the Counter-Terrorism Agency Suhardi Alius said that the return of the militants had triggered wariness over possible further spread of radicalism to communities and recruitment.

The chairman said that the agency would intensively monitor the movement of the IS' militants in the country, which has been frequently targeted by the global terrorists strikes.

"The thing they bring here is radicalism, it is on their brain," Suhardi said at the State Palace.

"There are still over 400 Indonesian citizens joining IS group's activities there (in Mosul of Iraq)," he added.

An offensive move launched by the Iraqi government against IS militants in Mosul city has led dozens of IS militants from Indonesia return to their country.

Recently, a series of strikes led by IS militants have been targeted to Western-link facilities and foreigners, police and churches in the country, leaving dozens of casualties and damages.

Indonesia has been included into the IS' global target as the top leader of group has ordered its militants to launch attack in their own countries, according to former security chief minister Luhut Binsar Pandjaitan.