Indonesian security forces have captured a Daesh-affiliated militant believed to have assumed leadership of the group after the country's most wanted man was killed in an operation.

The police chief of Central Sulawesi province told Anadolu Agency that Muhammad Basri was arrested Wednesday during an operation in which another member of the East Indonesia Mujahideen (MIT) was found dead in the troubled town of Poso on rugged Sulawesi Island. Another member of the group was shot dead.

"Basri has been captured alive in the jungles of Poso Pesisir," said Brig. Gen. Rudy Sufahriadi.

"Basri is prepared to replace Santoso," he added, referring to Abu Wardah Santoso who was killed in a shootout with police in July.

Basri is believed to have received military training as a member of the Jemaah Islamiyah -- al-Qaeda's Southeast Asia affiliate that was blamed for the 2002 Bali attacks that killed 202 people, mostly Australians -- between 2002 and 2006.

He was imprisoned in 2013 on charges of involvement in terror attacks targeting Christians and robbery, but managed to escape from detention.

Police have tagged him as a dangerous member of the MIT due to his reported role in the kidnapping and beheading of some Poso residents.

In addition to capturing Basri on Wednesday, police also recovered the body of a suspected militant that had been swept down a river.

According to Sufahriadi, the number of MIT members hiding in the mountainous area is has dropped from 40 in January to 13 with the latest arrest and death.

Santoso pledged allegiance to Daesh in 2014 and the government tightened security and focused its operation against his group after a Jan. 14 terrorist attack in central Jakarta killed four civilians and four Daesh-affiliated assailants.

His death was a major victory for authorities in the world's most populous Muslim-majority country.

Basri had been the deputy leader of the Eastern Indonesia Mujahideen, which has been hiding out in the jungles of Sulawesi for years but now has just a handful of members.

He was seen as a successor to Santoso, although it is not clear if he had officially taken over leadership of the group.

Santoso repeatedly evaded attempts to capture or kill him, with the long-haired, gun-toting militant regularly appearing in videos urging extremists to launch attacks.

The picture changed recently, with other Daesh-linked cells on the main island of Java considered a greater threat.