A bomb squad collected what appeared to be a pipe bomb attached to a mosquito coil near Ratchadaphisek Road, close to the Thailand Cultural Centre MRT Station, in Bangkok on Tuesday afternoon.
A taxi motorcyclist reported seeing the suspicious object while fishing in a deserted area behind a restaurant on the inbound side of Ratchadaphisek Road in Huai Khwang district about 2.40pm.
It was a steel pipe about 20 centimetres long and 10cm in diameter. The pipe was in a green plastic basket inside a black plastic bag.
Media reported that what looked like a fuse was attached to a lit mosquito coil, but rain had put it out.
A road cleaner said two men arrived on a motorcycle and the pillion rider spent about five minutes in the deserted area and they then sped off quickly on the bike.
Bomb experts took the object to Huai Khwang police station for examination.
About the same time police found a suspicious box beside Rama II Road in front of the Central Rama II shopping centre in Bang Khunthian district. Frontage lanes of the road were closed while it was examined - and found to be an empty box.
Later, national police chief Chakthip Chaijinda said the pipe bomb scene in Huai Khwang was cordoned off for officials to find more evidence as they had yet to find out the type, power and making of the bomb.
Officials would also have to find when it was placed, whether it had been discarded long ago and what the motivation was, he said.
The bomb was similar to the ones at Bangkok's Ratchaprasong intersection and Min Buri district years ago. Bomb experts would thoroughly examine its shrapnel and gunpowder, he said.
Pol Gen Chakthip said the latest pipe bomb might be intended to create disturbance or discredit the police. He said police intelligence did not point to the possibility of any more violent attack in the near future and police were trying their best to ensure public safety.
Police photos