Only one member of an al-Qaeda terrorist group entered Thailand as part of the plot to attack a US consulate and he has already fled to Malaysia, a Thai security source said on Wednesday.
The source said special branch police in Malaysia were preparing to apprehend the suspect, who has earlier been followed by Thai security officials.
The source said the United States consulate in Chiang Mai only wanted Thailand to beef up security for the US embassy in Bangkok, while the consulate itself had not taken any special security measures.
The US consulate in Chiang Mai remains open for visa services for tourists travelling to the US as usual.
The revelation of a possible terrorist attack in Chiang Mai might also be linked to the ongoing Cobra Gold exercise in the province, the source said.
The information followed a remark made earlier by Deputy Prime Mnister Chalerm Yubamrung that some of the al-Qaeda and Salafist terrorists had already left Thailand after the plan to attack the consulate was exposed.
Pol Lt-Gen Suthep Dejraksa, the Region 5 Provincial Police chief, said four to five more uniformed police had been added to the existing force guarding the front of the US consulate by the Ping River.
Plainclothes policemen had also been deployed on security duty around the consulate.
Police had been instructed to also keep a close watch on foreign tourists staying in houses for rent, guesthouses and renting cars, to ensure their safety, he said.