Authorities held about 60 people in various towns, some of them detained while distributing political leaflets Saturday, according to human rights group Suaram. Many were released after several hours of questioning, while the others were expected to be freed soon.

The arrests came as Prime Minister Najib Razak and National Police Chief Ismail Omar called on Malaysians over the weekend to shun an opposition-backed rally scheduled for July 9, saying it could spark chaos in Kuala Lumpur.

The opposition insists Najib’s National Front ruling coalition has long relied on fraud to manipulate election results and maintain its nearly 54-year uninterrupted grip on power. The government says current election laws are fair.

Independent political activists supported by opposition leader Anwar Ibrahim’s alliance are hoping to gather tens of thousands of people for a march to demand changes in election laws aimed at curbing fraud in the next national polls, which are widely expected within a year.

Human rights lawyer Malik Imtiaz Sarwar said the police appeared to be waging “a campaign of pre-emptive arrests” ahead of the rally.

“The police campaign appears to be aimed more at intimidation, apparently on the misconceived basis that this is a legitimate means to preserving public order,” Malik said.