Myanmar was due to submit a report to the United Nations' top court on Saturday (May 23) detailing what it has done to protect the minority Rohingya from genocide.
The International Court of Justice (ICJ) in January ordered Myanmar to safeguard the mostly Muslim group as part of "provisional measures" at the start of a trial expected to take years.
Gambia brought the case against Myanmar after a military "clearance operation" in 2017 forced over 730,000 Rohingya to flee to Bangladesh amid widespread reports of mass murder, gang rape, torture and arson.
Rohingya groups say Myanmar has ignored the ICJ's orders and the military is still committing atrocities in Rakhine state, where it is fighting ethnic Rakhine rebels.
"Myanmar has not taken any serious action to protect the Rohingya," said Muhammed Nowkhim, a Rohingya activist based in Bangladesh who fled the 2017 violence.
"Today they will lie in front of the international community," he told dpa.
It is unclear if the court will make the report public.
Nowkhim said refugee groups in Bangladesh have documented dozens of cases of Rohingya being killed or injured in Rakhine since the ICJ order, often by military shelling.
Myanmar last month issued directives to ministries and local governments saying officials and civilians must "not commit the acts mentioned in Articles II and III of the Genocide Convention."
Stella Naw, a Myanmar-based human rights activist, said the directives were disingenuous and aimed at shifting responsibility away from the military.
"They're always playing the same old game," she said.