YANGON (Reuters) - Three bombs rocked the capital of Myanmar’s restive Rakhine State, Sittwe, early on Saturday, police said, adding that a policeman was slightly injured and the authorities were still working to determine who was behind the bombings.

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The blasts come only three days after a large bomb killed two bank employees and injured nearly two dozen other people in the northeastern city of Lashio, where several ethnic insurgent groups are fighting the Myanmar military.

Sittwe is the capital of Myanmar’s violence-torn Rakhine where Rohingya Muslim insurgent attacks last year sparked a massive military response that pushed 688,000 Rohingya across the border into Bangladesh. Many of them recounted killings, rape and arson by Myanmar soldiers and police.

One of the Sittwe bombs - which went off around 4:30 a.m. - exploded in the backyard of an outspoken state government secretary, Tin Maung Swe, police said. He is one of the highest-ranking officials in the local administration. The other two bombs exploded near the high court and a land record office.

“There’re suspects, but now is not the time to talk. Police are trying to make sure about the suspects by analyzing the structure of the bombs,” police spokesman Colonel Myo Thu Soe, told Reuters by phone.

Myo Thu Soe also said three other unexploded hand-made bombs were found in the city.

The United Nations and the United States have called the crackdown on the Rohingya ethnic cleansing, but the government of Nobel laureate Aung San Suu Kyi has blocked U.N. investigators and other independent monitors from the conflict zone.

Myanmar says its forces have been engaged in a legitimate campaign against Muslim “terrorists”.

No one has claimed responsibility for the Saturday blasts. The twitter account of the Rohingya insurgents, the Arakan Rohingya Salvation Army, did not post anything new as of Saturday mid-morning.

Rakhine is also home to the Arakan Army, a Rakhine insurgent group.

Tensions have increased in Rakhine since mid-January, when Myanmar police shot dead seven demonstrators, while 12 people were injured in Mrauk U township in the northern part of the state, after a local gathering celebrating an ancient Buddhist Arakan kingdom turned violent.

Rakhine police chief Colonel Aung Myat Moe told Reuters that security was being tightened in the city and police were inspecting exit roads out of Sittwe.