Several individuals and organisations are being investigated under Section 124C of the Penal Code for allegedly attempting to undermine parliamentary democracy.
Critics have accused the authorities of using the law to stiffle dissent against Prime Minister Najib Abdul Razak.
But Dr Mahathir Mohamad, who is Najib's most vocal critic, appears to have escaped such a probe.
Deputy Home Minister Nur Jazlan Mohamed, however, indicated otherwise.
"Who says we are not investigating Mahathir under Section 124C?" he told Malaysiakini when quizzed on this.
"Whether or not we want to take this to the next stage is a different matter," he added, without elaborating.
Among those who are currently being probed under Section 124C are Bersih and their leaders including Maria Chin Abdullah, the Bar Council, Lawyers for Liberty, and Malaysiakini.
These probes are in relation to allegations that the groups received foreign funding, including from the George Soros-linked Open Society Foundations.
Deputy Prime Minister Ahmad Zahid Hamidi said the investigations are to determine if these groups are being funded to topple the government.
As of June this year, the police are investigating eight cases related to Mahathir.
This included a criminal defamation probe after the former premier claimed the Yang di-Pertuan Agong was under house arrest.
Meanwhile, Nur Jazlan said up to 20 NGOs are being probed for receiving foreign funds.
In response to this, eight human rights groups including All Women’s Action Society (Awam), the Centre for Independent Journalism (CIJ), and the National Human Rights Society (HAKAM) released a joint statement stating such funds were necessary due to the lack of government support.
The deputy home minister however reiterated his previous response that there was no need to be concerned if the groups had done nothing wrong.
He cited the probe into Malaysiakini, which has openly admitted to receiving funds from OSF, as an example.
"The government has not stopped Malaysiakini from operating," he pointed out.- Mkini