Myanmar's army has "killed and injured civilians in indiscriminate attacks since January 2019" as it battles the Arakan Army, a well-trained guerrilla force from the Buddhist ethnic group seeking autonomy for Rakhine, Amnesty said in a report.
It accused the military of carrying out "extrajudicial executions, arbitrary arrests, torture and other ill treatment, and enforced disappearances." But it also says the Arakan rebels have committed abuses against civilians, including kidnappings, though on a lesser scale.
"The new operations in Rakhine state show an unrepentant, unreformed and unaccountable military terrorizing civilians and committing widespread violations as a deliberate tactic," said Nicholas Bequelin, regional director for East and Southeast Asia at Amnesty International.
The group said it had written to top Myanmar government and military officials with specific questions about its findings and conclusions, but had not received any reply.
Rakhine is best known for a brutal counterinsurgency campaign launched by the military in 2017 against the Rohingya, which caused more than 700,000 to flee to neighboring Bangladesh. The army and other security forces were accused of major abuses, including organized rape, murder and the burning of villages.
Critics including U.N. experts have accused the Myanmar forces of ethnic cleansing, and possibly even genocide, but the government has insisted it was engaged in acceptable military operations after Rohingya guerrillas carried out attacks on police posts and bases.
While Rohingya insurgents have been largely inactive since late 2017, the Arakan Army has been engaged in increasingly fierce fighting with government forces since late last year. The group seeks autonomy for the region.
Amnesty International said it uncovered evidence of new abuses carried out by units implicated in previous atrocities.
The government declared the Arakan Army a terrorist organization after it killed 13 police officers and wounded nine in attacks on Jan. 4.
Last month, the main U.N. human rights agency expressed concern about the upsurge in fighting, especially attacks on civilians by both sides.
Ravina Shamdasani, a spokeswoman for the U.N. High Commissioner for Human Rights, said the agency had "credible reports of the killing of civilians, burning of houses, arbitrary arrests, abductions, indiscriminate fire in civilian areas, and damage to cultural property."