Police believe he planned attacks on the US embassy in Singapore and plotted to hijack and crash a plane at the city-state's international airport.
To help with the search, Interpol issued an Orange Notice - invoked after any event the France-based agency believes could pose a risk to the safety of people worldwide.
"Singapore is clearly doing all that it can on a national level to locate this fugitive," said Interpol's Jean-Michel Louboutin."Through issuing an Orange Notice, Interpol and all of its member countries can support these efforts on an international scale."
Kastari has been in detention since 2006 under Singapore's Internal Security Act.He was first imprisoned for immigration offences in Indonesia in 2003 and was extradited to Singapore three years later.
The authorities said he escaped after being granted permission to visit the toilet during family visiting hours at his detention centre.Police, Ghurkas and special forces are now reported to be involved in the search for Kastari, who walks with a limp.