Robertson warned that the admission it did not represent a change of heart from the military.
The pair have widely covered the military campaign in Rakhine although Reuters has declined to comment on whether they were specifically reporting on the mass grave in Inn Din.
Hundreds of thousands of Rohingya have fled Myanmar since August, when the army launched a bloody crackdown in response to attacks on border posts by the armed group, Arakan Rohingya Salvation Army. Myanmar officials refer to the Rohingya as Bengalis, a pejorative term used to imply they are illegal immigrants from Bangladesh. The ethnic Rakhine villagers panicked and went to a local Buddhist monastery, the statement said.
The military, in its account of the killings, said "200 Bengali terrorists" armed with sticks and swords attacked soldiers in the area on September 1. They fired guns into the air, scaring off the group except for 10 who were arrested, it said.
"The Convention on the Rights of the Child guarantees rights to health, education and opportunities to learn and grow to all children, irrespective of their ethnicity or status or the circumstances in which they find themselves".
"It was found that there were no conditions to transfer the 10 Bengali terrorists to the police station and so it was chose to kill them".
Security forces escorted ethnic Rakhine residents of Inn Din who led the way to the cemetery where the 10 Rohingya villagers, including Maung Ni's sons, were ordered to get into a pit in a ravine between two hillocks. 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.
The military denied all accusations of significant human rights abuses in a report released in November after an investigation.
The case has shocked Myanmar's embattled press corps. "This is the first time". The military said on Wednesday its investigation had found members of the security forces had killed the ten and that action would be taken against them.
More worryingly, it has emboldened nationalist voices who - like the military dictators that terrorised Myanmar - say journalists who challenge the official narrative should be punished for their treachery. "If someone violate these rules, action must be taken against him according to the law".
Ro Nay San Lwin, a Rohingya activist, said he did not believe the army's account of the incident.
Four members of the security forces also opened fire. "This reason is not acceptable".
Kyaw Kyaw Win, a lawmaker in the upper house of the national parliament whose constituency encompasses Maungdaw township, noted that it remains largely unknown whether the 10 Rohingya were terrorists, as the military claims. "What we do know is deeply troubling", said Marixie Mercado. The villagers were arrested from Inn Din beach on August 31, 2017.
US Ambassador Scot Marciel delivers an address on Myanmar-US relations in Yangon, May 10, 2016.
"The government are trying to show us that they still hold the power and that we can not report on whatever we want, even if we are doing the right thing and holding the government to account", he told Al Jazeera, a week after his release. "I would stress this should be done, not as a favour to the worldwide community, but because it's good for the health of Myanmar's democracy".
Meanwhile, the European Union on Thursday called for a credible investigation into Myanmar military's extrajudicial killings.
Reporting on both sides of the Rohingya crisis has proven hard for members of the foreign press who are prohibited from entering the conflict-torn areas of Rakhine state and rarely granted interviews with top government officials.
The Myanmar government, headed by one-time democracy icon Aung San Suu Kyi - has since been accused of "ethnic cleansing" by the US and the UN.
"This is not an issue of free press, it is a legal issue", said government spokesperson U Zaw Htay in a conversation with Al Jazeera.
The Myanmar government has also barred the media and some global NGOs from entering the conflict zone.
James Gomez, Amnesty's regional director for Southeast Asia and the Pacific, called the admission a positive development, but said it was "only the tip of the iceberg".
The U.N. and USA have said that the military campaign against the Rohingya has amounted to ethnic cleansing, while others have suggested that the army's actions may constitute genocide.