This follows the arrest of several leaders of the Parti Pribumi Bersatu Malaysia (Bersatu) Youth (Armada) recently.
"They are being interrogated, that is fine but the method used is wrong. They (MACC) were seen to be putting pressure where one of the Armada leaders was detained for four days.
"There was a lady who was interrogated in a dark room by five people."We are questioning the way they telephoned witnesses at night and stayed up until four in the morning, that is pressure," he said at a press conference here on Friday.
Earlier, several Armada leaders were arrested to assist in the investigation into the case of missing cash belonging to former Youth and Sports Minister Syed Saddiq Syed Abdul Rahman.