SINGAPORE - Two Singaporeans have been detained under the Internal Security Act (ISA) for terrorism-related activities, the latest in a trickle of such arrests here.

They are Abu Thalha Samad, 25, a member of terror group Jemaah Islamiah (JI), and housewife Munavar Baig Amina Begam, a 38-year-old naturalised citizen from India, said the Ministry of Home Affairs (MHA) in a statement on Thursday (Nov 9).

MHA said Abu Thalha had lived overseas for 15 years before his arrest, having been educated in JI-linked schools in the region, where he also received paramilitary training.

In 2014, he took an oath of allegiance and became a JI member.

"He understood it to mean that he was duty-bound to carry out whatever instructions the JI leaders had for him, including performing armed jihad and sacrificing his life for the JI's violent cause," MHA said.

Since 2016, he had been teaching at a JI-linked school, and was also on a committee that selected students for JI membership.

But in August this year, MHA said it worked with a "regional government" to deport him back to Singapore, where he was issued a two-year detention order in September.

It declined to disclose the country where he was in, but it is understood the JI terror group is active in Indonesia.

As for Amina, MHA said she was a supporter of the Islamic State in Iraq and Syria (ISIS) terror group, and had intended to travel to the Middle East to join ISIS.

"Amina was radicalised by a foreign online contact, who shared with her pro-ISIS materials, and convinced her that ISIS was fighting to defend Sunnis in the conflict zone," said MHA.

It also said she was prepared to undergo military training and take up arms and fight.

Amina, who was detained for two years this month, had also influenced others by sharing materials promoting terrorism on social media.

But her husband and her two children, who are Singaporeans, were unaware of her radicalism and were not implicated, said MHA.

Amina is the second woman to be detained under the ISA for terrorism-related activities.

The first was infantcare assistant Syaikhah Izzah Zahrah Al Ansari, 22, who was arrested in June. She had planned to travel to Syria to be a "martyr's widow".

Meanwhile, a third Singaporean, Adzrul Azizi Bajuri, was issued a restriction order after he was radicalised by ISIS propaganda online.

The order limits the activities of the 19-year-old, a former full-time national serviceman, and requires him to undergo religious counselling.

Adzrul, who was serving as a logistics assistant in the Singapore Armed Forces when he was arrested, had come across ISIS-related videos in 2014 when he was a secondary school student, watching videos on the Israeli-Palestinian conflict, MHA said.

Although he had considered fighting for the group, he started "having some doubts about the legitimacy of ISIS ideology and its violent tactics" in August, said MHA.

MHA noted that his relatives and people around him had seen indications of his radicalism. One of them even tried to counsel him, but none reported him to the authorities.

"Adzrul's radicalisation was left unchecked because no one came forward to report him. Fortunately, he was detected before he could engage in armed violence overseas," said MHA, adding that there were no signs that Adzrul had radicalised any of his fellow NSFs.

Neither were Abu Thalha or Amina reported by their relatives or friends, said MHA, which also stressed that the three arrested did not have plans to carry out attacks here.

"(Adzrul's) case and others this year show how challenging it is for the authorities to detect individuals who are self-radicalised," it said.

"It is therefore critical that if people are aware that someone they know is radicalised, they should quickly report to the authorities, before the individual gets involved in terrorist conduct."

The action taken against the trio means that about 20 Singaporeans have been dealt with under the ISA for terror-related activities since 2015.

Muslim community leaders said the latest moves were a reminder that the terror threat - particularly that posed by JI - was active in the region, and that Muslims should be discerning when viewing religious material online.

Minister-in-charge of Muslim Affairs Yaacob Ibrahim urged Muslims to seek religious knowledge from accredited religious teachers, and get help from the Islamic Religious Council of Singapore (Muis), the Religious Rehabilitation Group (RRG), or the police if they see signs of radicalisation.

"If we do not seek help, we do them and our community irreparable and grave harm should they act on their misguided beliefs," said Dr Yaacob, who is also Minister of Information and Communications.

Ustaz Irwan Hadi Mohd Shuhaimy, Muis' deputy director of religious policy and regulation, said social media was not the appropriate platform to receive religious instruction, especially not in "understanding complex political and armed conflicts in the Muslim world".

Other religious leaders, like Ustazah Zhahirah Mohammad Salleh, who is part of the Asatizah Youth Network, said many of those radicalised online accept extremist material unquestioningly.

"I would advise them to cross-check with religious teachers, or even their parents. They should communicate with another person instead of just with their computer screens," she said.

On Thursday, MHA also said a separate restriction order against former Moro Islamic Liberation Front member Mustafa Kamal Mohammad had been allowed to lapse in September, as the 62-year-old had been rehabilitated.