SINGAPORE - Singapore must not let conflicts elsewhere affect the trust and harmony between different races and religions here, said Prime Minister Lee Hsien Loong.

The country has to try its best to insulate itself from conflicts and quarrels in other countries such as Iraq and Syria, he said, adding that those battles are not fights for Singaporeans.

Addressing about 300 community leaders on Monday (July 24) before a closed-door dialogue at ITE College Central, PM Lee said attacks inspired by terror groups such as the Islamic State in Iraq and Syria (ISIS) or Al Qaeda can "affect perceptions and attitudes of Muslims and non-Muslims" in Singapore.

"We have to expect the recent spate of ISIS inspired attacks in the world, what is happening in the Middle East, in our region... to have caused some doubts and qualms among Singaporeans," he said.

Muslims feel they are under the spotlight, while non-Muslims may worry about whether they can still trust Muslims, he noted.

Fortunately, racial and religious harmony in Singapore is strong as religious leaders of all faiths have worked hard to promote inter-faith dialogue and interactions, he said.

"But we have to keep up this effort, to repair the harm done by external events, and to strengthen the trust between the different faiths," he added, so that communities will not turn against each other when an attack happens here.

In his speech, PM Lee also highlighted the terrorism threat worldwide and in the region, as well as how Singapore remains a target.

While the country might be an "oasis of peace", it is not disconnected from the rest of the world. He pointed out that Singaporeans who were self-radicalised have been motivated by ISIS ideology and conflicts in the Middle East.

"When we see religious conflicts elsewhere, we have to remind ourselves those are not our fights. Whatever the problems in Syria or Iraq, they are not our problems," he said.

And while ISIS might be on the defensive in the Middle East - having lost its Iraqi stronghold of Mosul - it remains a "magnet for religious extremists", PM Lee said.

Its followers could disperse and return to the South-east Asia region, which he said is on the "frontline" of the war against terrorism.

Prominent terrorists have been actively recruiting more fighters from Malaysia and Indonesia and directing attacks in countries including Singapore, he noted.

Last week, the Jakarta- based Institute for Policy Analysis of Conflict (Ipac) said in a report that the terrorist network responsible for the ongoing siege of the Philippine city of Marawi had urged militants to attack targets in Singapore, Thailand, Myanmar, South Korea, Japan and China.

PM Lee said ISIS has also been using the fighting in Marawi as propaganda to recruit more fighters, which it has directed to the Philippines.

It was "unrealistic" for Singapore to think it can be unaffected by all of this, he said.

He cited a foiled plot by an ISIS-linked group last year to launch a rocket at the Marina Bay Sands from the Indonesian island of Batam. The authorities know of other planned attacks that have not been carried out yet, he added.

The developments in Singapore are just as worrying, said PM Lee, highlighting three trends.

First, the authorities here have discovered foreign workers who have been radicalised.

It has repatriated Indonesians, including maids, with links to ISIS. Over the last two years, 40 Bangladeshi workers, who had formed a radical group here and were planning attacks in their home country, were also arrested.

Second, Singapore is seeing a steady trickle of self-radicalised individuals. "We pick up one every month or two," PM Lee said.

Last month, three Singaporeans were arrested under the Internal Security Act (ISA) for terrorism-related offences.

Auxiliary police officer Muhammad Khairul Mohamed, 24, was detained for planning to travel to Syria to fight against the Syrian government, while infant care assistant Syaikhah Izzah Zahrah Al Ansari, 22, had planned to travel to Syria to become a "martyr's widow", fighting for ISIS.

Khairul's colleague Mohamad Rizal Wahid, 36, was also placed on a Restriction Order for supporting his plan.

Both Khairul and Izzah were radicalised after viewing extremist propaganda online.

These cases will not be the last, PM Lee warned.

He added that the psychological impact would be much worse if Singaporeans carried out a terror attack here, compared to an attack by foreign terrorists.

A third worrying trend is how extremist and exclusivist teachings, which reject accommodation with other faiths and divide Muslims from non-Muslims, are creeping in to the mainstream religious narrative here.

Such practices could see Muslims being told not to shake hands with non-Muslims, forbidden from wishing well believers of other faiths during holidays such as Christmas or Deepavali, and barred from following non-Muslim leaders.

If these teachings gain ground, it will weaken racial harmony and make Singapore more vulnerable to extremist terrorism, PM Lee said.

"It will also encourage a backlash - there will be Islamophobia, non-Muslims will see Muslims in a bad light... which is just as bad and unacceptable," he added.

PM Lee noted that different religions have co-existed in Singapore for more than a hundred years.

He pointed to areas such as Telok Ayer Street or South Bridge Road, where there are places of worship of different religions.

"Our religious leaders understand the need for accommodation. They reject extremist ideologies, and oppose exclusivist teachings. All the communities live side by side, interact with one another, and practise their own faiths and customs peacefully," he said.