The handling of case 003, which the government opposes, has set off a raft of complaints from victims groups and legal experts.
It remains unclear under what authority the court would
pursue such action.
Court observers say the statement from OSJI and the submission of Cayley do not necessarily signal a problem at the court.
The UN-backed court’s investigating judges have come under fire in recent weeks after they made a preliminary conclusion to Case 003.
At least five key staff members have left the Khmer Rouge tribunal’s investigating judges’ office since April.
International prosecutor Andrew Cayley said in a public statement last month he would file for further investigation in the case 003.
The court has come under increased criticism of political interference and a lack of funding.
The Council is expected to announce a four-year rotation of judges and prosecutors, including retirees, on Wednesday.
Under the Khmer Rouge, Muslims were forced to break major tenets of their religion, including eating pork and frequent prayer.
The judges have also ordered Cayley to retract portions of a public statement involving Case 003.
The procession included monks from Burma, Japan and Thailand, as well as Cambodia.
Sam Rainsy alleges Hun Sen was responsible for the deaths of people sent to clear forests along the Thai border in the 1980s.