Manila — Philippine journalist Maria Ressa, whose news site has repeatedly clashed with President Rodrigo Duterte, was arrested at her Manila office on Wednesday  in what press freedom advocates branded an act of “persecution”.

Her detention on a charge of “cyberlibel” is a dramatic escalation in government pressure bearing down on Ressa and her website Rappler, which was already facing tax evasion charges that could shut it down.

It comes after Duterte has cracked down on high-profile critics in the press and legislature who dared oppose his signature anti-drug campaign, which has killed thousands.

“She’s been arrested and she’s been read her rights,” Rappler co-founder Beth Frondoso told AFP. Later, Rappler announced in a tweet that Ressa would have to spend the night at the National Bureau of Investigation, the unit that detained her, as lawyers tried to find a court to post bail.

Ressa, who was named a Time Magazine Person of the Year last year for her journalism, left the Rappler offices with plainclothes officers and surrounded by cameras. “The case is ridiculous and the fact that they issue an arrest warrant is a travesty of justice,” Ressa told journalists after her arrest. “This is what journalists in the Philippines now have to go through.” 

Rappler has drawn the administration’s ire since publishing reports critical of Duterte’s so-called war on drugs, which critics say has targeted the poor and could amount to crimes against humanity.

However, the new case against Ressa and former Rappler reporter Reynaldo Santos Jnr stems from a 2012 report written about a business person’s alleged ties to a then judge in the nation’s top court. While investigators initially dismissed the business person’s 2017 complaint about the article, the case was subsequently forwarded to prosecutors for their consideration.

Philippine journalists immediately attacked the surprise serving of the warrant at Rappler headquarters. “The arrest of ... Ressa on the clearly manipulated charge of cyberlibel is a shameless act of persecution by a bully government,” said the National Union of Journalists of the Philippines. “The government ... now proves it will go to ridiculous lengths to forcibly silence critical media.”

Amnesty International also swiftly condemned the arrest as “brazenly politically motivated”. “In a country where justice takes years to obtain, we see the charges against her being railroaded,” the group said in a statement.

The Philippines tumbled six places last year in the Reporters Without Borders rankings of press freedom to 133rd out of 180, with the body noting that the government has pressured and silenced critics.

Duterte has lashed out at other critical media outfits, including the Philippine Daily Inquirer newspaper and broadcaster ABS-CBN. He threatened to go after their owners over alleged unpaid taxes or block the network’s franchise renewal application.

Some of the drug crackdown’s highest-profile detractors have wound up behind bars, including senator Leila de Lima, who was jailed on drug charges she insists were fabricated to silence her.

Ressa insists the site is not anti-Duterte, saying it is just doing its job to hold the government to account.

The law that forms the foundation of the case takes aim at various online offences, including computer fraud and hacking.

Presidential spokesperson Salvador Panelo said the cases against Ressa had nothing to do with her work as a journalist. “This has nothing to do with freedom of expression or the press,” he told broadcaster ABS-CBN. “Regardless of who commits any crime, he or she will be charged in accordance with the law.”

In the tax case, the government accuses Rappler, Ressa and the site’s accountant of failing to pay taxes on 2015 bond sales that it alleges netted gains of 162.5 million pesos ($3m).

The Philippine justice system is notoriously overburdened and slow, with even minor cases taking years to be judged.