KUALA LUMPUR (Feb 23): Singaporean authorities have deported four Indonesians believed to be on the way to the Middle East to join the Islamic State of Iraq and Syria (Isis), reports The Straits Times.

Quoting a source familiar with the case, the Singaporean daily said the four suspects, including a 15-year-old boy, were arrested at Woodlands Checkpoint as they were making their way into Singapore from Johor.

Identified as Muhammad Mufid Murtadho, Untung Sugema Mardjuk, Mukhlis Koifur Rofiq and Risno, they are linked to radical ideologue Aman Abdurrahman, said Indonesian national police chief Badrodin Haiti yesterday.

Police investigations seem to indicate that Aman might have ordered the Jan 14 attack in Jakarta from his jail cell in Nusakambangan prison, but it is unclear if the three men and boy deported from Singapore are involved in the hit on the capital.

Authorities took notice of them when they took a ferry from Batam to Singapore before heading to Johor, and then returning to Singapore three hours later.

According to The Straits Times, the four were handed over to Indonesian police at Batam Island on Sunday.

The deportation comes after Australia on Sunday warned that a terror attack against Kuala Lumpur was in the works.

This followed the Jakarta attacks in January which saw at least eight people dead, of which four of them were attackers.

Isis has claimed responsibility over the incident, prompting high alert in Southeast Asia, which is also the base of Katibah Nusantara, a dedicated Isis military unit.

Malaysian police say that they will continue to patrol the capital to convince residents and visitors that Kuala Lumpur is safe.