He identified Sabah as one of the trouble areas in Southeast Asia, but did not give specific details. Other places in his list are the Philippines and Myanmar.
He said he had interviewed terrorists captured in Malaysia, Singapore and Indonesia.
Gunaratna heads the International Centre for Terrorism Research and Political Violence at the S Rajaratnam School of International Studies in Singapore.
Speaking at a conference on financial crime and terrorism financing here, he urged national governments, religious institutions, enforcement agencies and banks to pool knowledge in order to counter the spread of terrorism.
He said it was crucial to cut the financial sources of terror groups, adding that this required the profiling of groups and personalities with suspected links to terrorism. “There is a need to constantly create new personality profiles. Look out for family trees, including the widows.”
He said banks must monitor financial transfers to conflict zones to make sure that the funds go towards genuine humanitarian needs.
He said terrorists had been known to present fake identity cards to banks to order money transfers. He gave the example of a terrorist who did this to buy weapons worth US$30,000 to US$40,000.
Other methods would include the use of counterfeit money and fake credit cards, he added.
He also called for alertness against cyber fraud.
He said a terrorist he interviewed in Singapore told him his superior in Langkawi had used Bitcoin to transfer money to buy weapons.
Gunaratna also spoke of hostage taking as a source of funding for terrorists. He said terror groups were increasingly interested in kidnapping citizens from western countries because these countries had paid millions to free their citizens.
He also warned that women were actively recruiting other women into terror groups through social media.
During his interviews with women terrorists, he said, they told him they believed they would turn into men on their way to heaven if they were killed in a jihad.