People who take part in Saturday's mass "No Kings" protest against President Donald Trump's administration may be targeted for federal government surveillance with a range of technology that could include facial recognition and phone hacking, civil libertarians said.

"No Kings" organizers expect 2,600 rallies across all 50 US states. But the level of surveillance at protests and the type of technology in use is likely to be both location-specific and dependent on the police forces present, said Thorin Klosowski, a security and privacy activist with the Electronic Frontier Foundation, said Friday.

For instance, crowds in Washington, DC, where anti-scale fencing has been erected around the White House complex, are likely to be surveilled differently than those in a small rural town.

"Under previous administrations, law enforcement surveillance of peaceful demonstrations was already commonplace and corrosive of free expression," Ryan Shapiro, executive director of government transparency group Property of the People, said in an email Friday. "Given Trump's open hostility to even minor dissent, such surveillance now poses an existential threat to what remains of American democracy and only underscores the need for mass protest."

The Department of Homeland Security's Immigration and Customs Enforcement has been implementing Trump's immigration crackdown and has amassed a digital surveillance arsenal, according to various news outlets.