By Agence France-Presse
More than 700,000 Rohingya Muslims were forced to flee Rakhine state after a military crackdown that the United Nations has said amounts to "ethnic cleansing".
Myanmar's military has denied targeting the stateless minority and said it was defending itself against Muslim militants who attacked police posts in August 2017.
But a new report from Amnesty said army commander-in-chief Min Aung Hlaing and 12 other senior military and security officials oversaw an orchestrated campaign of violence in the restive state where the Rohingya have been historically marginalized.
"The ethnic cleansing of the Rohingya population was achieved by a relentless and systematic campaign in which the Myanmar security forces unlawfully killed thousands of Rohingya, including young children," said the report.
It also accused security forces of sexual violence, torture, forced displacement and burning markets and farmland that starved communities and forced them to flee.
"These crimes amount to crimes against humanity under international law, as they were perpetrated as part of a widespread and systematic attack against the Rohingya population," the report said.
The report said some senior military figures and border guard police oversaw units that directly carried out alleged atrocities, while others knew of subordinates' actions and failed to prevent, stop or punish the crimes.
The 186-page document is the first attempt to name and implicate senior figures in the widespread violence that sparked the mass exodus and humanitarian crisis that followed.
Hundreds of thousands of Rohingya have settled in squalid camps in neighboring Bangladesh, many too scared to go back despite a repatriation agreement with Myanmar that rights groups have said does not guarantee a safe return.
The report is the most detailed account of the crisis to date and follows fresh sanctions from the European Union this week against seven security officials accused of serious crimes including sexual violence and killings.
Min Aung Hlaing was not subject to the sanctions but six people on the EU list are also named in the Amnesty report, which is based on more than 400 interviews in Myanmar and Bangladesh from September 2017 to June 2018.
The authors also used satellite imagery, forensic analysis and confidential military documents.
The report also details alleged abuses carried out by the Arakan Rohingya Salvation Army (ARSA), the Muslim militant group that attacked police posts on August 25, 2017.
It said ARSA killed informants and people with military links and massacred dozens of Hindus in the area, which the militant group has denied.
Amnesty says it requested a response from Myanmar's military and the office of de facto leader Aung San Suu Kyi but did not receive a reply.
Myanmar has previously rejected calls for an ICC probe, arguing that it is not party to the treaty that governs the court.