Suspected militants set off small bombs inside and outside at least 21 banks in predominantly Muslim southern Thailand today.
The bombs killed at least one person and wounded more than 20.
They were stashed in rubbish bins, hollowed out books and public phone booths at the banks in Yala province near the Malaysian border, police said.
A retired civil servant was killed by an explosion in the provincial capital of Yala in a rash of explosions similar to one across the three Muslim-majority provinces of the far south in June that killed at least two people.
An anonymous caller warned one bank it had been targeted, prompting people to flee minutes before an explosion, police said. More than 1,100 people have been killed in secessionist violence since January 2004.
Many of today's bombs were set off by mobile telephone, and at least one was defused before it could go off.
Two suspects were held for questioning and the authorities believed most of the devices were planted by students.
The three provinces of Yala, Narathiwat and Pattani, where the majority of people are ethnic Malay, were a sultanate until annexed by overwhelmingly Buddhist Thailand a century ago.