A 37-year-old Penang-born man has taken his Singaporean family to Syria where they are believed to be in different locations fighting alongside jihadists or supporting them.
His Singaporean wife was a 47-year-old widow who had a daughter and a son - aged 18 and 14 - from a previous marriage, The Star newspaper reported on Friday.
The report quoted sources as saying the family went to Syria in November, but did not stay together.
"The authorities believe the man joined the Jabhat Al-Nusra group and his stepson the IS (Islamic State),'' the sources told the newspaper. IS is also known as the Islamic State in Iraq and Syria (ISIS).
"The wife worked as a cook while the daughter taught English to the children of the fighters in Syria," one source was quoted as saying.
The family members are believed to be in different parts of Syria, according to the newspaper. One possible location is east Hama, where jihadists are known to have set up a base of operations.
Authorities are keeping close tab on the family and trying to find out how they were influenced to go to Syria, said the report. The sources said the authorities believe their decision had to do with the woman's former husband.
In July, Singapore's Deputy Prime Minister Teo Chee Hean disclosed in parliament that several Singaporeans are among 12,000 foreigners taking part in the armed conflict in Syria, including a couple of parents who had taken along their children
Among the "handful" of Singaporeans is said to be a woman who went with her foreign husband and their two teenage children.
"The whole family is taking part in the conflict in various ways, either joining the terrorist groups to fight, or providing aid and support to the fighters," said Mr Teo, who is also Singapore's Home Affairs Minister.
Another man, Haja Fakkurudeen Usman Ali, 37, took with him his wife and three children between the ages of two and 11. He is a Singapore citizen who was an Indian national, the Home Affairs Ministry had said in March when announcing that he was under investigation.
Several other Singaporeans had planned to join the conflict but were detained before they could set off, and some others were under investigation, said Mr Teo.
The Star newspaper had earlier reported that five former Internal Security Act detainees are among 40 Malaysians who have joined the militants.
The five named include 45-year-old former Kedah PAS Youth information chief Mohd Lotfi Ariffin, who was injured in an attack which killed the youngest Malaysian jihadist in Syria on Tuesday. Mohammad Fadhlan Shahidi Mohammad Khir, 21, from Kedah was the second Malaysian jihadist to be killed in Syria.
The first Malaysian militant to die in Syria was Abu Turob, 52, who was killed during an attack by tanks and snipers on Aug 19.
In Putrajaya, Malaysian Home Minister Datuk Seri Dr Ahmad Zahid Hamidi called on Malaysians to reject extremist views and protect the country's image. He said the actions of a few individuals did not reflect the true nature of the country and its people.
"We don't want Malaysia to be presumed internationally as a breeding ground for terrorists (and) we must protect the image of our religion and country based on the principle of moderation or wasatiyyah.
"This principle has to be defended by all citizens. We have to avoid being extreme left or extreme right."