BANGKOK, Jan. 1 (Xinhua) -- A bomb went off at a mosque in Thailand's northern province Chiang Mai, on Monday morning, injuring a cleaner of Myanmar nationality, local police confirmed.

    Police sources told Xinhua that the explosion took place around 9 a.m. (0200GMT) Monday morning at a mosque at the provincial seat of Chiang Mai, the hometown of ousted premier Thaksin Shinawatra.

    The northern province, a popular destination, was hosting a three-month International Horticultural Exposition that will close at the end of January.

    The expo site, located on the suburb of the provincial seat, was holding New Year celebrations when a series of bombings hit Bangkok on early New Year's eve and shortly after midnight, killing three persons and injuring some 40 others.

    Sonthi Boonyaratkalin, the army chief and chairman of Thailand's military-led Council for National Security, would cut short his pilgrimage trip to Mecca, Saudi Arabia, and return to Thailand on Monday afternoon.

    An earlier report, quoting Thailand's independent TV station iTV, said a grenade was lobbed into a mosque in Chiang Mai, injuring four people.

    Meanwhile, several school fires were reported earlier in Thailand's northern and northeastern provinces, which were considered the strongholds of Thaksin and his Thai Rak Thai party.

    Suspicions spread that these were arson attacks.