A small bomb struck a Bangkok military hospital on Monday wounding more than 20 people, police said, three years to the day since the army seized power of the politically unstable kingdom. 


Thailand remains starkly divided since the May 22, 2014 coup, but dissent has broadly been silenced by a military with sweeping security powers. 


It was not immediately clear who was behind the blast but the country has a long history of small bombs being used by various political and militant groups, especially during significant anniversaries. 


Police investigations rarely get to the bottom of who is culpable for the attacks. 


Monday's blast struck a pharmacy inside a military hospital in Bangkok, stirring panic among patients and sending smoke into the corridors but causing only minor injuries. 


"From the initial report it was a bomb... there are more than 20 people injured," Deputy National Police Chief General Srivara Rangsibrahmanakul told reporters. 


"It was likely to be in a package," Srivara said, adding that "battery and wires" were found at the scene. 


The clinic in central Bangkok -- King Mongkut Hospital -- is often used by serving and retired members of Thailand's armed forces. 


Police said the hospital was not evacuated while bomb disposal officers scoured the scene. 


Medical emergency staff at the Erawan Rescue Centre said 24 people were injured. 


Police are already hunting suspects behind two other small blasts in recent weeks, but have given conflicting and contradictory information over the devices and likely suspects. 


Last Monday a small pipe bomb detonated outside Bangkok's National Theatre, close to the Grand Palace. 


On a subsequent walkabout Bangkok's city police chief declared the explosion was caused by a broken water pipe, only to later backtrack when other officials briefed it was a small homemade bomb. 


Since the coup the political violence that defined much of the last decade had subsided, although peace has largely been achieved through repression. 


Public demonstrations and political gatherings are banned while dissidents and critics are often arrested on charges of sedition, breaching junta orders or under the draconian royal defamation legislation. 


Militant elements among pro-democracy groups have either been arrested or have gone to ground. 


Over the past 10 years Thais have witnessed repeated rounds of deadly protests, a string of short-lived governments and two military coups that deposed elected leaders. 


The junta says its 2014 coup -- the 12th time generals have successfully seized power -- was needed to bring stability and root out corruption. 


But critics say the military is far from being a neutral player, deeply hostile to ousted premiers Thaksin and Yingluck Shinawatra, whose parties have won every poll since 2001. 


Their billionaire clan is popular among Thailand's rural and urban poor and they have urged a return to elections. 


But the Shinawatras are hated by Bangkok's military-backed elite, who accuse the family of corruption and nepotism. 


In a statement on Facebook to mark the coup Yingluck decried a lack of "concrete reform" warning three years of military rule risked becoming a "waste of time".

Source: NNA