National police chief Khalid Abu Bakar said in a statement late Thursday that the 15, aged between 22 and 49, included four women, a police official, an airplane technician, a mosque cleric and a student.
Khalid said the 15 were detained over three days from Tuesday in Kuala Lumpur and six other states. He said they had allegedly received orders to launch attacks in the country from a Malaysian man who had joined the Islamic State in Syria.
The group also arranged for two foreign terror suspects to sneak out of Malaysia into a Southeast Asian country, he said, without giving details. They were also involved in raising and channeling funds to a militant group in the southern Philippines, and in recruiting new members, Khalid said.
The four women were planning to go to Syria to join the Islamic State, he said.
Malaysia has raised its security alert level following the January 14 attacks in neighboring Indonesia, and on January 15, police said they had detained a man who was hours away from carrying out a suicide attack in Kuala Lumpur.