A woman originally from India was among three Singaporeans arrested under the Internal Security Act (ISA) for supporting the Islamic State and terrorism- related activities, authorities said today.

Of the three, Adzrul Azizi bin Bajuri (19) was issued with a Restriction Order, while Abu Thalha bin Samad (25) and Munavar Baig Amina Begam (38) were issued with Detention Orders, the Ministry of Home Affairs said in a statement.

Amina, a housewife and a naturalised Singapore Citizen originally from India, is an ISIS supporter and harboured the intention to make her way to the conflict zone to join ISIS, the ministry said.

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

"She was radicalised to the extent that she was prepared to undergo military training and take up arms to fight for ISIS in the Middle-East if called upon by ISIS to do so," the statement said.

She shared on social media materials promoting terrorism. This month, she was issued a Detention Order for a period of two years.

Of the two men, Abu Thalha was found to be a member of the terrorist group Jemaah Islamiyah (JI). He was educated in JI-linked schools in the region and also underwent paramilitary training in some of the schools he attended.

"In 2014, he took baiah (pledge 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 JIs violent cause," the ministry said.

He has been teaching in a JI-linked school since 2016 and had also served in a committee which was involved in spotting students for membership in the terror group.

"In August 2017, we worked together with a regional government to deport him to Singapore where he was arrested under the ISA for his involvement in a terrorist organisation. He was issued with an Order of Detention for a period of two years in September 2017," the ministry said.

Adzrul, a former full-time National Serviceman who served as a Logistics Assistant in the SAF, is a supporter of the terrorist group Islamic State in Iraq and Syria, it said.

"In mid-2016, Adzrul considered fighting for ISIS in Syria, as he saw the armed conflict there as a sectarian struggle between Sunnis and Shias. From August 2017 onwards, he started having some doubts about the legitimacy of ISISs ideology and its violent tactics," the ministry said.

It said that Adzrul will be required to undergo counselling, including religious counselling.