Ugaz said he has asked Minister in the Prime Minister's Department Datuk Paul Low about the donation but was told only the Prime Minister can answer his question.
"We had a meeting two days ago. His statement was - the one who needs to explain is the Prime Minister, not him, not the Commission or the Attorney-General," Ugaz said.
Ugaz said he was hoping to meet Najib during the conference and had tried contacting the Prime Minister's Office for a meeting.
"He said he was coming but he cancelled it last time. So it hasn't been possible.
"We have been contacting his people for months," he said.