Dozens of bombs exploded almost simultaneously at police stations, checkpoints and government offices in Narathiwat, Pattani and Yala, southernmost provinces where more than 1,300 people have been killed in two years of separatist insurgency.
The biggest explosion hit a teashop in front of Kokpoe police station in Pattani province, killing a Buddhist councillor and wounding 10 customers, a Kokpoe police officer said by telephone.
''This teashop is usually a meeting place for police, but luckily none of us was there this morning,'' the officer said.
Bombs were also planted in a toilet of Yala City Hall and a toilet in the Yala police station, police said.
The army and police said the bombs, mostly small time-bombs using wrist watches to set them off around 0100 HRS (2330 IST Wednesday), were designed to make noise rather than kill.
''Judging from the size of the bombs and the time of the explosions, they just wanted to wreak havoc, not take lives,'' army spokesman Thanathip Sawangsaeng said.
The bombs went off during a visit by Deputy Prime Minister Chidchai Vanasatidya, who is in charge of national security, to tighten security.
The government of overwhelmingly Buddhist Thailand has tried many ways to end the violence and win the hearts and minds of the 1.8 million people in the far south, an independent Muslim Sultanate until annexed by Bangkok a century ago.
It has tried everything from brute force to promises of development aid, but militant attacks on security forces, officials and ordinary people continue almost daily in the region, where most people speak a Malay dialect.