Bomb attacks at two night markets in Chiang Mai on Tuesday caused property damage but did not injure anybody.
At around 11pm on Tuesday, a grenade thrown into Kad Luang market caused a fire, which was quickly put out. A number of broken bottles containing kerosene were found near the blast site.
Earlier, another explosion took place at a pedestrian area not far from Waroros Market, causing property damage.
Deputy provincial governor Phairoj Saengphoowong said the red shirts were not behind these attacks and that it was really motorcycle racers who were fined and arrested during the curfew hours and now wanted to vent their anger. However, provincial chief Maj-General Sommai Kongwisaisuk said vendors who had returned from the red-shirt rally in Bangkok could be behind both bomb attacks.
Meanwhile, the officer said police had arrested three more men suspected of torching two government buildings on May 19, in addition to three men arrested earlier. A Bt10,000-per-head bounty is being offered for the many other men suspected of creating unrest on the same night.
In Udon Thani, police arrested two disc jockeys of community radio stations - Prasit Wichairat and Jakkraphong Saenkham - for airing anti-government propaganda and inciting hatred. Both suspects have denied the charges.
Of the total 71 arrest warrants issued in Udon Thani, 11 people have been arrested with seven indicted so far.
In Khon Kaen province, 152 arrest warrants have been issued for rioters and 20 have been arrested for taking part in May 19 riots when the city hall, an NBT station and a Bangkok Bank branch were torched.