The violence in southern Thailand failed to stop the talks in Kuala Lumpur between Thai security officials and representatives of Barisan Revolusi Nasional, which was suspected in the explosion, the Bangkok newspaper The Nation reported.
A member of the government delegation to the talks expressed hope the violence would eventually decline.
Noting that BRN was the largest organization involved in the unrest, National Security Council Secretary-General Paradorn Pattannathabutr said, "I am confident that they will communicate our message to their militants, but because BRN is a large organization, we have to give them time."
Three rangers were killed and five others wounded, two seriously, in Narathiwat province when a roadside bomb exploded while village militia members were on patrol, The Bangkok Post reported.
The attack occurred near the village of Ban Cho Kroh, the home of a wanted separatist leader for whom a $170,000 reward has been offered for his capture.
More than 5,300 people have been killed in clashes between government forces and insurgents in Thailand's majority-Muslim provinces.