The Amnesty International report said in the last few months Myanmar soldiers have killed and wounded civil in indiscriminate attacks in Rakhine state, Efe news reported.
It is the same area where the Army in 2017 carried out an offensive against the mostly-Muslim Rohingya minority group, an operation the UN said showed evidence of genocidal intent.
In the report titled "No one can protect us: War crimes and abuses in Myanmar's Rakhine State", the non-profit also denounced atrocities committed by the Arakan Army, such as abductions and intimidation, but accused the Myanmar military of committing human rights violations such as extrajudicial executions, arbitrary arrests, torture and other ill-treatment, and enforced disappearances.
"Less than two years since the world outrage over the mass atrocities committed against the Rohingya population, the Myanmar military is again committing horrific abuses against ethnic groups in Rakhine State," Nicholas Bequelin, Amnesty International's regional director for East and Southeast Asia, said in a statement.
The report is based on 81 interviews, 54 of which were conducted on the ground in Rakhine, with people of different ethnicities and religions.
The Arakan Army, one of the various rebel groups engaged in armed conflict in Myanmar, was formed in 2009 by students of the Rakhine ethnic group - which is predominantly Buddhist.
( With inputs from IANS )