Singaporeans say they are prepared for a terror attack, but only one in five believes it will happen here.

But the Ministry of Home Affairs (MHA), which released its second Singapore Terrorism Threat Assessment Report yesterday, warned that the terrorism threat remains high.

As part of the report, a survey conducted last year by MHA of 2,010 citizens and permanent residents aged 15 and above found that only 20 per cent felt an attack might occur in Singapore in the next five years.

And only 60 per cent felt that Singapore could be targeted.

Noting the uncovering of more radicalised individuals here and the continued global presence of terror groups, MHA said "it is important for Singaporeans to not become complacent".

The report noted the significant threat from terrorist group ISIS and others such as Jemaah Islamiyah regrouping in South-east Asia, and they may again launch large-scale attacks.

The number of self-radicalised individuals have risen significantly, with 14 Orders of Detention (OD) and eight Restriction Orders (RO) issued since 2015, compared with just five ODs and six ROs from 2007 to 2014.

Radicalisation among foreign workers also remains a concern, with MHA revealing five more Indonesian domestic workers have been repatriated for being radicalised, bringing the total to 14 since 2015.

While there is no credible intelligence on an attack being planned against Singapore since 2017, the security agencies remain on high alert, said MHA.

"We will not hesitate to take action against any individual propagating pro-violence or segregationist religious teachings, whatever the religion," it added.

MHA also noted that SGSecure - the national terrorism awareness movement - has helped make people more vigilant to potential threats.

Three in four of the survey respondents said they are alert and prepared for a terror attack.

Associate professor Kumar Ramakrishna, head of policy studies and national security studies at the S. Rajaratnam School of International Studies, Nanyang Technological University, said the survey results are "not that surprising", owing to Singapore not having a terrorist incident since the 1970s.

"At an intuitive, psychological level, Singaporeans may feel that the Government has been doing such a great job of protecting the country that it will always be able to do so," he said.

"This is the paradoxical, unintended consequence of our successful counter-terrorism policies and strategies."

He said the possible issue with such perceptions is that Singaporeans may be "unconsciously unprepared" for a terror attack here.

"It has always been a challenge for the authorities to persuade the public not just at an abstract, intellectual level but also at a deeper, intuitive level, that one must be alert to the threat at all times, but of course not to the extent of being overly alarmed," he said.

"In countries that have experienced such attacks, the public arguably needs less persuasion as they have had first-hand experience and fully acknowledge the reality of the threat."

The MHA report acknowledged that the Government's measures are not foolproof.

"Even as the Government has put in place measures to enhance our counter-terrorism ability, the authorities will not be able to uncover and prevent every threat," it said.

Singapore Red Cross secretary-general and chief executive Benjamin William said: "It is important that Singaporeans pick up emergency preparedness skills... (but) it is still a challenge to get the public to see matters like first-aid training and blood donation as a personal and national priority.

"Singaporeans may have grown accustomed to living in a safe country, and so they take security for granted."