MANILA >> The award-winning head of a Philippine online news site that has aggressively covered President Rodrigo Duterte’s administration was arrested today by government agents in a libel case.

Maria Ressa, who was selected by Time magazine as one of its Persons of the Year last year, was arrested over a libel complaint from a businessman which Amnesty International condemned as “brazenly politically motivated.” Duterte’s government said the arrest was a normal step in response to the complaint.

Duterte has openly lambasted journalists who write unfavorable stories about him, including his anti-drug campaign that has left thousands of mostly poor suspects dead.

Rappler Inc., the news site which Ressa heads, said National Bureau of Investigation agents served the warrant late this afternoon, making it difficult for Ressa to apply for bail, and escorted her from the Rappler office to NBI headquarters.

“We are not intimidated. No amount of legal cases, black propaganda, and lies can silence Filipino journalists who continue to hold the line,” Ressa said in a statement. “These legal acrobatics show how far the government will go to silence journalists, including the pettiness of forcing me to spend the night in jail.”

(U.S. Sen. Brian Schatz condemned the arrest. “I am deeply concerned by reports that journalist Maria Ressa has been arrested on trumped-up charges in the Philippines,” the Hawaii Democrat said in a news release. “These charges should immediately be dropped, and Ms. Ressa should be free to go about her work. Instead of trying to silence journalists who are accurately reporting the news, the Filipino government should focus on protecting democracy and defending the country’s constitution, including its commitment to a free press. I also call on the U.S. government to condemn this arrest, and stop giving cover to strongmen who want to erode press freedom.”)

Ressa and a former Rappler researcher, Reynaldo Santos Jr., were indicted recently, the Department of Justice said.

Rappler said the businessman filed the libel complaint five years after the article appeared in 2012, and the law under which Ressa was charged by the government, the Cybercrime Prevention Act, did not go into effect until months after the article’s publication.

The article included allegations that the businessman was linked to illegal drugs and human trafficking, and that a car registered in his name had been used by the country’s chief justice.

Amnesty International Philippines said, “This is brazenly politically motivated, and consistent with the authorities’ threats and repeated targeting of Ressa and her team.”

Justice Secretary Menardo Guevarra said the arrest was “merely part of any criminal procedure.” Duterte’s spokesman said the charge against Ressa was based on facts which she should simply answer and had “nothing to do” with press freedom.

Rappler is one of several news agencies deemed critical of Duterte’s policies.

Duterte had already banned a Rappler reporter from his news briefings after the government’s corporate watchdog said the news site violated a constitutional prohibition on foreign ownership of media when it received money from an international investment firm. Rappler, founded in 2012, rejected the ruling.

Ressa has also posted bail on tax evasion charges which she denies and says were politically motivated.

The International Press Institute, a global network of media personnel, strongly condemned Ressa’s detention.

“The arrest of Maria Ressa is an outrageous attempt by the Philippines government to silence a news organization that has been courageously investigating corruption and human rights violations in the country,” IPI director of advocacy Ravi R. Prasad said in a statement.

“The manner in which Ressa has been pursued by the government by slapping legal cases against her is not only shameful but also a gross and willful violation of press freedom.”

In its selection of Ressa as a Person of the Year, Time magazine cited her and several other journalists as “guardians” in what it said was an effort to emphasize the importance of reporters’ work in an increasingly hostile world.

Ressa, who has worked with CNN, also was the winner of two prestigious journalism awards last year, a Press Freedom award from the New York-based Committee to Protect Journalists, and the International Center for Journalists’ Knight International Journalism Award.

Honolulu Star-Advertiser staff contributed to this report.