Western governments have warned travellers to exercise extreme caution in Myanmar after a series of minor bomb blasts, including one at an upmarket hotel that injured an American woman.
Britain, France, the United States and Australia all urged their nationals to be vigilant, although they stopped short of advising against travel to the former junta-ruled country.
"There is a high threat from terrorism," the British foreign office said in updated advice following a blast at the Traders Hotel in Yangon late on Monday.
"Attacks could be indiscriminate, including in places frequented by foreigners. The motivation for the attacks is at present unclear," it added.
The hotel bombing and two earlier blasts in Mandalay came as Myanmar prepares to host the Southeast Asian Games, a major regional sporting event, in December and chair the Association of Southeast Asian Nations next year.
Observers said the small explosions were likely aimed at stoking panic and harming reform efforts by the new quasi-civilian government, rather than causing mass casualties. No group has claimed responsibility.
The injured American was taken to hospital with wounds to her thigh and her hand after a blast tore through her room at Traders, which is popular with foreign tourists and business people.
Officials said they detained a 26-year-old suspect early on Tuesday in the southeastern state of Mon on suspicion of violating the explosives act and causing serious harm to others. He had previously stayed in the room at the Traders Hotel where the blast occurred.
The man, Saw Myint Lwin, had been under surveillance for alleged involvement in the planting of a second device found at a restaurant the next afternoon, police said. Officers matched his photograph with images captured on the Traders Hotel closed-circuit television camera, according to a statement issued by Mon state police.
The Traders Hotel is owned by Malaysian billionaire Robert Kuok's Shangri-La Asia. Kuok controls Kerry Group, which is the biggest shareholder in SCMP Group, publisher of the South China Morning Post.
Additional reporting byAssociated Press