Acting Bangkok police chief Pol Lt-General Sanit Mahataworn said police were seeking information from the immigration bureau about 600 Indian nationals who have entered and left the country, to try and identify the body. The man is believed to be of Indian ethnicity, and may have hailed from the border of Bhutan.

The body was dropped close to where it was found in the canal, because the watergate had been closed and water was not flowing at the time.

Sanit said the man might have been killed at least three days ago.

Police have also interrogated the owner of a shop selling suitcases and fashion bags on Mahachai Road. The shop owner said an Indian-looking man, around 150-centimetres tall, plump and in his 40s bought two Bodium brand bags for Bt350 each. The man was allegedly speaking in Punjabi. The shopkeeper will be summoned today to describe the suspect’s face to an official sketch artist.

Sanit said police also checked guesthouses in the 850-metre perimeter of the canal and also walked along the waterway to locate the site where the bag holding the body was thrown.

Police suspect the perpetrators may be staying at Burapa or Meerama hotels because they are located between two bridges and the canal. The 2-metre deep canal was dredged on Friday.

He said the criminals had bought the bags three days ago and physical examination of the body indicated that the man had been dead for at least three days.

Since the canal is not deep enough during the day, police believe the bag must have been dropped into the water between 7pm and 9pm.