SINGAPORE - A 51-year-old Singaporean man who was on his way to join militant group Islamic State in Iraq and Syria (ISIS) in Syria has been detained under the Internal Security Act (ISA), the Ministry of Home Affairs said in a statement on Tuesday (July 28).

Mustafa Sultan Ali is the first Singaporean to be arrested abroad for trying to join ISIS, which has attracted some 30,000 foreign fighters to territory it controls in Syria and Iraq, including some 1,000 from South-east Asia.

He also told Singapore authorities that he was prepared to carry out attacks in Singapore.

Mustafa, whose occupation was not disclosed, had left Singapore in late May this year for a neighbouring country.

He then boarded a flight to Turkey from there.

He took that travel route in the hope of hiding his tracks, the ministry said.

He had planned to cross into Syria from the Turkish border, but was detained by local authorities in Turkey and subsequently deported to Singapore in June 2015.

"Investigations showed that Mustafa had been deeply radicalised by the terrorist ideology of ISIS and other radical ideologues he had come across online," the statement added.

"He had travelled to Turkey and tried to make his way to Syria in order to participate in armed violence by fighting alongside ISIS.

"Mustafa also said that he was prepared to carry out ISIS-directed terrorist attacks against Western establishments in Singapore," the statement said.

At least two Singaporeans are known to have gone to Syria to join ISIS, and both had taken their families and young children along. They are still believed to be there.

In May, a 19-year old radicalised student was also detained under the ISA for planning to join ISIS. Last month, a radicalised 17-year old was also issued with a restriction order.

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If he was unable to leave Singapore, the 19-year-old had planned to assassinate government leaders here, including the President and Prime Minister.

Security authorities in the region are also concerned that their citizens fighting in Syria will pose a major threat when they return home.

Several radical groups in the region have also pledged allegiance to ISIS, and some of them have links to Jemaah Islamiah, whose Singapore chapter had planned to set off truck bombs here in 2001.

The Ministry of Home Affairs said the Government takes a very serious view of any form of support for terrorism, including but not limited to the use of violence, and will take firm and decisive action against any person who engages in such activities.

Anyone who is aware of a person involved in terrorism-related activities or who sees suspicious activities should inform the Internal Security Department on 1800-2626-473 or the Police by calling 999, it added.

yanliang@sph.com.sg