Human Rights Watch on Monday called for Myanmar to punish army and police commanders if they allowed troops to rape and sexually assault women and girls of the Rohingya Muslim minority.

The New York-based campaign group said it had documented rape, gang rape and other sexual violence against girls as young as 13 in interviews with some of the 69,000 Rohingya Muslims who have fled to Bangladesh since Myanmar security forces responded to attacks on border posts four months ago.

"The sexual violence did not appear to be random or opportunistic, but part of a coordinated and systematic attack against Rohingya, in part because of their ethnicity and religion," a Human Rights Watch (HRW) news release said.