In a statement, the military said that due to the fighting they could not transport the men so the detainees were executed by soldiers and local villagers instead of being handed over to police.
Suu Kyi rarely speaks to the media and has said little in public about the crisis in the western state.
The military announced on December 18 that a mass grave containing 10 bodies had been found at the coastal village of Inn Din, about 50 km (30 miles) north of the state capital Sittwe.
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Wa Lone and Kyaw Soe Oo covered the unrest in Myanmar's northwestern Rakhine state, where some 655,000 Rohingyas have been forced to flee into Bangladesh to escape a scorched earth campaign against them by military forces.
Refugees who have fled in their hundreds of thousands to Bangladesh have given consistent accounts of massacres, rape and torture by Myanmar security forces flanked by ethnic Rakhine mobs.
A military investigation on the mass grave found near Inn Din village in Maungdaw township concluded the Myanmar's security forces broke the Rules of Engagement and was responsible for the killings, according to a military statement. The army appointed a senior officer to investigate.
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On Wednesday, it admitted that ethnic Rakhine villagers and security forces killed the 10 Royingya Muslims in the village on September 2 a year ago.
Government forces had been conducting a "clearance operation" in a region about 30 miles north of the state capital of Sittwe when "200 Bengali terrorists attacked using sticks and swords".
"We have made a decision to provide the aid in response to the agreement between Myanmar and Bangladesh to represent an worldwide message of support so that the repatriation can be carried out promptly", said Foreign Ministry official Shinobu Yamaguchi in a statement.
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Myanmar insists that the Rohingya minority are illegal migrants from Bangladesh, hence the references to "Bengalis" in official statements.
Angry ethnic Rakhine Buddhist villagers, who had lost relatives in militant attacks, wanted to kill the captives, and stabbed them after forcing them into a grave on the outskirts of the village. Then members of the security forces shot them dead, the military said.
The military denied all accusations of significant human rights abuses in a report released in November following an investigation.
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Human rights organization Amnesty International claimed the admission exposes the extrajudicial killings of Rohingya, marking a "sharp departure from the army's policy of blanket denial of any wrongdoing".