Nine suspected militants have reportedly been arrested by Indonesian police in Sulawesi island on Friday (10 March). The arrests came after the police operation targeted a group who allegedly had affiliations to the Islamic State (Isis) extremist group.

Police spokesman Martinus Sitompul, however, declined to provide more details as investigations are still underway.

Media reports suggested that police seized bomb-making materials from the place where the suspected militants were hiding out. The explosives included fertilisers, sulphur and nails and were reportedly meant to launch an attack against police forces, according to Reuters.

"They were planning to damage the police station and other vital objects in the region of Central Sulawesi," national police spokesman Rikwanto was quoted as saying by Anadolu Agency.

The suspects were all thought to be members of the Mujahidin Indonesia Timur group, which until a few months ago had been under the control of one of the first Indonesian jihadists who pledged allegiance to Isis.

Some of the militants are still thought to be hiding in a dense jungle in Sulawesi's troubled Poso town, where Indonesian security forces have been conducting a months-long operation to nab more such extremists linked to Isis.

The leader of the Mujahidin group, Abu Wardah Santoso, was killed in a shootout in July 2016. He was the world's largest Muslim-majority country's most-wanted man. Since then, Indonesian authorities have been expecting reprisal attacks in the region.

Santoso's militant group was reportedly the first Indonesian group to swear loyalty to Isis in 2014. He was designated as a terrorist by the US after his group launched an attack in January 2016 in the heart of capital Jakarta, killing four civilians and four militants.

Authorities in Indonesia have claimed to have foiled several attacks during Christmas season last year after conducting a series of raids, raising concerns over the home-grown militants expanding in the country.

Earlier in February, police killed an extremist after he set off a small bomb in Bandung city. Authorities were determining if the deceased militant had links to the Isis.

Indonesia police
Indonesian authorities arrested nine militants allegedly linked to Isis as the world's largest Muslim-majority country faces a growing threat from supporters of Isis ~ file photoERLANGGA MAHAMERU/AFP/Getty Images