Twenty-seven male Bangladeshis working in the construction industry in Singapore have been arrested under the Internal Security Act (ISA).

All of them were arrested between Nov. 16 and Dec. 1, 2015, the Ministry of Home Affairs (MHA) said on Wednesday, Jan. 20, 2016.

All 27 have had their work passes cancelled, and 26 of them have since been repatriated to Bangladesh, where the authorities were informed of the circumstances of their repatriation.

The last person is set to be sent back after serving a jail term for attempting to illegally leave Singapore after finding out about his fellow members' arrest.

Investigations showed that they supported the armed jihad ideology of terrorist groups such as Al-Qaeda and the Islamic State in Iraq and Syria (ISIS).

They were not planning any terrorist attacks in Singapore but some of them had considered waging armed jihad overseas.

Of the 27, 26 were members of a closed religious study group that subscribed to extremist beliefs and teachings of radical figures like Anwar al-Awlaki, an American and Yemeni Islamic lecturer alleged to have ties with militant group Al-Qaeda.

Awlaki was killed in a drone strike in Yemen in September 2011.

Although not a member of the study group, the remaining man supported extremist preachers and possessed jihadi-related material and was discovered to have been undergoing radicalisation.

The Internal Security Department recovered a "significant amount" of radical and jihadi-related material during investigations.

Several members also possessed a shared document with graphic images and instruction details on how to conduct "silent killings" using different methods and weapons.

Books and videos containing footage of children undergoing training in what appeared to be terrorist military camps were also found.

The MHA also said the group members shared jihadi-related materials discreetly, held weekly gatherings to discuss armed conflicts involving Muslims, while taking measures to avoid detection by the authorities and targeted the recruitment of other Bangladeshi nationals to grow their membership.

Several contemplated travelling to the Middle East to take part in the ongoing conflict.

Some of them were in support of terrorist groups that killed Shi'ites as they considered Shi'ites to be "deviant".

They also bore grievances against the Bangladeshi government over its actions against some Islamic groups and leaders and had also sent monetary donations to entities believed to be linked to extremist groups in Bangladesh.

Pasir Ris-Punggol GRC Zainal Bin Sapari has taken to Facebook to appeal to Singaporeans to be mindful of this event and its implications, while emphasising that "The workers arrested are not typical of a Bangladeshi worker".