Post offices in Chiang Mai have impounded more than 2,000 letters believed mailed by some ill-intent political elements to scuttle the draft constitution which is due to go through a referendum on August 7.
The mysterious letters seized in Chiang Mai are similar to those earlier impounded in Lampang. The letters do not have the names of the receivers or the senders but just the addresses of the receivers. Most were however stamped.
Mr Boontham Prasongvarakit, chief of the post offices in Chiang Mai, the letters in question were found to have mailed through mail boxes in Sansai, San Kamphaeng, San Pakhoi, Mae Rim and Mae Jo districts.
Military and police officials were called in to help examine the letters now kept at the central post office in Muang district.
Maj-Gen Kosol Prathumchart, commander of the 33 military circle, said that all the letters would be handed over to the Election Commission for further examination.
He said that if the letters were found to be illegal, then a formal complaint would be lodged with the police so that legal actions could proceed.
Meanwhile, officials were dispatched to put up announcements warning people who have received the letters not to believe in what was written in the letters.