Indonesian police confirmed Monday the arrest of a leader of Jemaah Islamiyah, the Southeast Asian wing of international terrorism network al-Qaida, saying he was building a fighting force and an economic base to set up a caliphate in Indonesia when arrested.

National Police spokesman Dedi Prasetyo told a press conference that Para Wijayanto, 54, who had been at large since 2003, and his wife were arrested by the counterterrorism police unit Detachment 88 at a hotel in Bekasi, in the suburbs of Jakarta, on Saturday.

"The suspect has been actively involved in a series of terror attacks in Indonesia, from the Christmas Eve bombings in 2000, the Bali bombings in 2002 and the bombing at the Australian Embassy in 2004," Dedi said, referring to a series of bomb attacks that killed 18, 202 and nine people respectively.

Para, known as the "crown prince of JI," has been on the police radar since being found to have had intensive communications with some of the most dangerous JI figures, including the Bali bombing perpetrators.

The engineering graduate of the Diponegoro Public University was named JI emir or leader in 2008 due to his good organizational skills, although his religious knowledge was limited.

Under his leadership, Dedi said, Jemaah Islamiyah has been building a clandestine military wing and recruiting new fighters on campuses.

"From 2013 to 2018, the suspect had sent six batches of new recruits to Syria to attend military training and directly practice (to get involved in a war) in Syria," the senior police officer said.

Since 2014, the Jemaah Islamiyah under Para, which is later called "neo-JI" by police, has actively campaigned against Islamic State militants for quickly condemning anyone refusing to join the group as infidels.

In Syria, the neo-JI fighters joined militant group Jabhat al-Nusra to fight against Islamic State and its emir Abu Bakr al-Baghdadi.

According to Dedi, after practicing their skills in Syria, they have started to return to Indonesia since May.

"Most of the returnees have capabilities in intelligence, making bombs, operating rockets and having skills as snipers," he said.

"At the moment, we haven't seen any plan from them to launch terror attacks, but they are now at the stage of building force aimed at setting up a caliphate in Indonesia," he added, saying all of those in the organizational structure have received salaries between 10 million rupiah (about $709) and 15 million rupiah.

The police spokesman revealed that the group is also developing an economic base, opening palm oil plantations on the islands of Sumatra and Kalimantan.

Terrorism researcher Mohamad Adhe Bhakti said it was apparently preparing new terror attacks by "producing weapons," modifying airsoft guns and replacing their bullets with iron ones.

According to him, the group, whose strongholds are on Java Island and Lampung Province on Sumatra Island, frequently holds paramilitary training in the towns of Klaten and Kendal in Central Java Province.

"Although its popularity has been covered by IS, special attention must be given to this group because this is an alternative group for the supporters of al-Qaida in Southeast Asia" Mohamad told Kyodo News.

Before joining Jemaah Islamiyah, Para used to work as an engineer at a giant company in Central Java. In early 2000, he took part in military training on the southern Philippine island of Mindanao.

"Police were difficult to catch him because he always uses burqa," Mohamad said, referring to an enveloping outer garment worn by women in some Islamic traditions to cover themselves in public.