The announcement could not be independently verified in an region that has been seized by communal violence since Rohingya militant raids on August 25 triggered a sweeping security crackdown.
"Security members found and dug up 28 dead bodies of Hindus who were cruelly violently and killed by ARSA extremist Bengali terrorists in Rakhine State," a statement posted on the army chief's website said.
The Arakan Rohingya Salvation Army (ARSA) is the group whose attacks on police posts triggered an army backlash so brutal that the UN believes it amounts to ethnic cleansing of the Muslim minority.
Some 30,000 Hindus and Buddhists based in the area have also been displaced, with some saying were terrorised by Rohingya militants.
More From This Section
The army said that security officers found 20 dead women and eight men in the graves, including six boys under the age of ten.
Myanmar government spokesman Zaw Htay confirmed the discovery of the 28 bodies on Sunday.
A senior police officer in northern Rakhine told AFP they had been "buried with 10-15 bodies in each hole."
The village where the army chief said the bodies were found, Ye Baw Kya, is near a cluster of Hindu and Muslim communities in northern Rakhine called Kha Maung Seik.