TRAVEL WARNING TO INDONESIA -Indonesia's most wanted terrorist Possible counterattack

Members of the Indonesian Military (TNI) cross a river in Poso in Central Sulawesi

The Central Sulawesi Police have warned civilians and security personnel alike to remain alert to the possibility of a counterattack from Indonesia's most wanted terrorist, Santoso, as Operation Tinombala enters its fourth month.

The operation, launched in January with the involvement of more than 3,500 Indonesian Military (TNI) and police personnel, has yet to lead to the capture of the terrorist also known as Abu Wardah.

Security personnel including military elite troops have combed the forested Napu Valley spanning four districts of Poso regency - North Lore, Central Lore, East Lore and Lore Peore - in search of Santoso and fellow members of the East Indonesia Mujahidin (MIT) group.

The joint forces are believed to have cornered the group following the intensification of the search in the Napu Valley, but the fugitive remains on the loose.

Operation Tinombala personnel have also been following up villagers' reports of sightings of unknown men in the village of Sanginora in Poso Pesisir Selatan subdistrict.

Security authorities believe that Santoso's guerillas, who have pledged allegiance to the militant group Islamic State (IS), were previously hiding in Tamanjeka forest, on Mount Biru and in other parts of Poso Pesisir.

 Operation Tinombala is a successor to similar joint operations ongoing since 2013.

Operations Camar Maleo I, II, III and IV were launched last year to no avail, although Santoso's right hand man, Daeng Koro aka Sabar Subagyo aka Antatrawa, was killed during a shootout in Parigi Moutong.

 Operation Tinombala had so far led to the deaths or arrests of 10 members of the MIT. The group is now down to 29 people, including three women, Rudy said.

Operation leaders have blamed the local geography for the lack of success so far.

Santoso's hideaway was in  primary forest spanning 7,000 kilometers of mountainous terrain.