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

-Rappler fighting numerous cases lodged by government

-Charges 'brazenly politically motivated', says Amnesty

-Government denies stifling media, says libel committed

For all latest news, follow The Daily Star's Google News channel.

Her detention on a charge of "cyber libel" 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 that 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 which detained her, as lawyers tried to find a court to post bail.

Ressa, who was named a Time Magazine "Person of the Year" in 2018 for her journalism, left the Rappler offices with plain-clothes 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," she added.

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

'FORCIBLY SILENCE CRITICAL MEDIA'

However, the new case against Ressa and former Rappler reporter Reynaldo Santos, Jr stems from a 2012 report written about a businessman's alleged ties to a then-judge on the nation's top court.

While investigators initially dismissed the businessman'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 cyber libel 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," it added.

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 Reporters Without Borders rankings of press freedom to 133rd out of 180, with the body noting 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 had 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 spokesman 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 Holdings Corp., 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 ($3 million).

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