Batam news media have reported the existence of flyers and letters warning of bomb attacks at a number of locations in Batam and Bintan.
The attacks are reportedly aimed at Singaporean travellers, and travellers from Johor.
The flyers and letters claim that the attacks will take place at the Batam Center Ferry Terminal, the Batam region of Nagoya, Bintan Telani Ferry Terminal and the Bintan region of Tanjung Pinang.
The notes claim that militants who were planning the attacks arrived in Riau 2 weeks ago.
Tanjung Pinang police have confirmed that the flyers exists and they are conducting investigations.