The three, namely lawyers Fadiah Nadwa Fikri and Amer Hamzah Arshad; and Suaram executive director Nalini Elumalai are being probed under Section 66 of the Societies Act 1966.
According to that section, any individual under suspicion of having information on the existence or operation of any illegal society or on the operations of any registered society can be summoned.
When contacted, Fadiah (left) described the continuous investigation against Suaram as a form of harassment and attempt to impede its work, which includes pursuing alleged kickbacks in the RM7.3 billion purchase of two Scorpene submarines by Malaysia in the French courts.
"This is a form of harassment and intimidation for advocating on the Scorpene scandal.
"ROS has no jurisdiction over Suaram. We are registered under the Companies Commission of Malaysia (CCM), not ROS," she said.
The trio were served with a notice by ROS on Thursday and are to present themselves at its Putrajaya headquarters at 11am today.
Several individuals were already questioned on Nov 12.
KLSCAH dragged into probe
Meanwhile, in a widening investigation against Suaram, police on Wednesday also visited the Kuala Lumpur Selangor Chinese Assembly Hall (KLSCAH) which has frequently played host for Suaram press conferences.
When contacted, KLSCAH chief executive officer Tang Ah Chai (right) said the police made copies of documents on transactions between Suaram and KLSCAH.
"The policemen came at around 2pm and stayed for an hour. They finished their investigation by photocopying some copies of rental forms and payment receipts by Suaram," he said.
Tang said this was not the first time police had gone after KLSCAH which sits along Jalan Maharajalela in Kuala Lumpur. A similar incident happened when Hindraf held its event there in 2008.
He added that the KLSCAH venue is open for rent to all and such problems from the authorities should not arise.