May 6 (Reuters) - A mixed martial arts fighter who joined anti-coup protests in Myanmar was wounded by a homemade bomb and later arrested, the military said on Thursday, among blasts in at least three cities as the junta battles to assert its control of the country.
Phoe Thaw, 36, was arrested in hospital while receiving treatment for leg wounds sustained while testing a home-made bomb late on Wednesday at a Yangon gym, the military's Myawaddy TV reported.
He was among four people detained and accused of colluding to commit violent acts, it said.
Small blasts are becoming more frequent in towns and cities in Myanmar, some at government or military buildings, which the junta says are proof of a violent rebellion by supporters of Aung San Suu Kyi's ousted government.
A unity government comprised of former politicians, pro-democracy groups and ethnic minority armies says the explosions are being orchestrated by a junta seeking to cling to power by eradicating its enemies.
Myanmar has been in chaos since a Feb. 1 coup, which ended a decade of economic reform and tentative steps towards democracy initiated by the military after 49 years of rule in the impoverished but resource-rich country.
Months of protests and strikes have crippled the economy, disrupting banking, business and much of the bureaucracy, prompting concern that Myanmar is edging closer to becoming a failed state.
Explosions took place on Wednesday at a bus station in Mandalay as well as at a bank and a military-owned telecoms company in the capital Naypyitaw, MRTV reported, prompting a call by junta leader Min Aung Hlaing for "effective action" against the perpetrators.
"They are destroying the country," MRTV quoted him saying.
It also reported that arrest warrants were being sought for 40 medical workers and teachers accused of promoting a civil disobedience campaign.
Fighter Phoe Thaw is well-known in Myanmar and was pictured during the protests holding a sign that challenged Min Aung Hlaing to a cage fight.
Images on Myawaddy TV on Thursday showed him on a stretcher, with legs covered in wounds and burns.
A former colleague, who spoke to Reuters on the condition of anonymity, said the home-made bomb had been left at the gym car park by a policeman posing as a civilian.
The incident comes days after the military reported five people, including a politician in Suu Kyi's party, were killed in an explosion in the Bago region, with bomb-making materials recovered from the scene.
Media outlets Irrawaddy and the Democratic Voice of Burma on Thursday said a local government administrator was knifed to death in Mandalay, the second such killing this week, after the fatal stabbing of a junta-appointed official in Yangon.
At least 769 people have been killed and nearly 3,700 detained by Myanmar's military since the coup, according to the Assistance Association for Political Prisoners (AAPP), a monitoring group outlawed by the military.
Reuters has not been able to independently verify casualty numbers due to restrictions on media. Many reporters have been detained and news organisations ordered closed, deemed by the junta to be instigators of unrest.
The junta banned satellite television receivers on Tuesday to block outside broadcasts, adding to months of curbs on internet services.
More than 200 civil society groups on Wednesday urged the U.N. Security Council to impose an arms embargo on Myanmar, the latest call for global action against the generals, who have historically been impervious to international criticism.
The coup has unleashed anger across Myanmar among people unwilling to tolerate another era of military rule.
More youths took to social media on Thursday to declare their intent to train to fight in the unity government's newly formed "defence force", threatening to attack the well-equipped military if more civilians are killed. (Reporting by Reuters Staff; Writing by Martin Petty; Editing by Hugh Lawson)