All six of the wounded were hurt by a bomb that went off near a branch of state-owned Krung Thai Bank in the Ra-Ngae district of Narathiwat province, police said.
The second bomb exploded earlier in Ruso district, also in Narathiwat province, but injured no one, police said.
Police were initially called to a house fire but as they were about to leave the scene, the bomb, which was hidden near the house, went off, Ruso police station superintendent Colonel Watcharin Ammarapitak said.
"But nobody was injured," he added.
A third bomb, believed to be detonated by mobile phone, exploded at a university in nearby Yala province, severely wounding one Buddhist lecturer and a female Muslim student, police said.
A fourth explosive device was defused by police.
Thaksin was expected to leave Bangkok around midday on Wednesday for a three-day tour of the southernmost provinces of Narathiwat, Yala and Pattani.
Narathiwat is one of the three provinces in the far south near the Malaysian border where more than 500 people have been killed since January last year, with no end to the violence in sight.
Thaksin will start a three day tour
of southern Thailand
But Thaksin, due to meet both Muslim and Buddhist leaders during his first visit since his resounding re-election win earlier this month, said there would be no change of policy in an area where he did not win a single seat.
"We will resort to a policy of both iron-fist and velvet gloves in dealing with the south," Thaksin was quoted by Thai newspapers as telling a cabinet meeting on Tuesday.
The cabinet decided to set up a new 21,000-strong army division to be based in the far south to replace a similar number moved in from other bases.