Two bomb related incidents took place yesterday, one detonated in the deep South possibly by insurgents which wounded three policemen, and the other in Chiang Mai as a bomb scare intended to merely cause disruption.

At around noon, the roadside bomb attack in Narathiwat wounded three policemen and caused property damage.

It was planted near a busy petrol station in Ra Ngae district, blasting at a police pickup which the three wounded officers were occupying while causing damage to another three vehicles.

Police said the homemade bomb, using 5 kg explosives contained in a metal box and detonated through a mobile phone, could have buried at the site after 9 pm Wednesday night after the petrol station was closed.

They did not say whether political motives were behind the explosion, as the site was also located near the home of Matuphum Party MP Najmudeen Uma.

Two of the officers are still in critical conditions and being treated in Songkhla's Hat Yai district, where 50 people donate blood for their surgeries in an hour's time after a request for blood was made public.

The one not seriously wounded is receiving treatment in Narathiwat.

In Chiang Mai at around 9 am, a bomb was found planted at a bus stop in front of a school in Chiang Mai's Pa Tong district, before it was disposed of by a bombs disposal robot.

The bomb, contained in a potato ship can with its detonator powered by a pair of batteries, was active and ready to go off if detonated, said police ordnance personnel.

Police said the incident was intended to merely cause disruption, but did not comment about who could be behind it.

Responding to the Chiang Mai bomb scare, Prime Minister Abhisit Vejjajiva said he was considering lifting the state of emergency in Chiang Mai, which is a stronghold of antigovernment red shirts, and other tourist frequented provinces anyway in the next week regardless of the incident.

"Chiang Mai is one the provinces being put under consideration over revocation of the emergency state, as the business sector are complaining about effects on tourism," he added.