The police will record statements from Bersih chairperson Maria Chin Abdullah and Merdeka Center programme director Ibrahim Suffian over allegations that their groups were funded by billionaire George Soros.
"I received this evening, asking me to go to Bukit Aman tomorrow morning at 10.30am," Maria told Malaysiakini.
The police did not reveal what law was being applied for the investigation, she said.
Ibrahim, meanwhile, said police asked to record his statement next Monday.
"I was called this morning because there was a report lodged against me.
"I was told to appear at the Dang Wang district police headquarters on Monday morning at 10am," he said.
Ibrahim, however said he needed to check if he had other commitments on that morning.
The police officer who contacted him did not review which provision he will be probed, he said.
Bersih and Merdeka Center were implicated by several news organisation in their reports on the leak of grant making group Open Society Foundation (OSF), which was founded by Soros.
The news reports focused on OSF's Malaysia programme which funded groups which promoted free and fair elections.
This was interpreted as attempts to interfere in Malaysia's electoral process.
Bersih was not mentioned in the leaked OSF document but the news reports still linked the two together.
Maria was quoted saying Bersih had not received grants from the OSF and the National Democratic Institute since 2011, relying only on local sources for funding.
The leaked OSF document, however, did mention Malaysiakini as the recipient of funds from the OSF.
According to Malaysiakini CEO Premesh Chandran, the funds were meant for video projects in Sarawak and that Malaysiakini was not in the business of overthrowing any government.
Premesh said that the amount was only a small portion of Malaysiakini's revenue, which was largely derived from subscription and advertising.
However, the police have established a five-member team to investigate the news organisation under Section 124c of the Penal Code, for carrying out activities detrimental to parliamentary democracy.-Mkini