MANILA - A move to "silence" the press.

International media groups, journalists and rights advocates have scored the arrest of Maria Ressa, chief of Philippine news website Rappler, as they condemned the blow on press freedom.

Renowned journalist Christiane Amanpour, formerly Ressa's colleague at international news network CNN, called the administration of President Rodrigo Duterte "desperate" in taking a journalist into custody.

"You know a government is desperate when they arrest a journalist. President Duterte: FREE @mariaressa NOW," said Amanpour in a tweet Thursday night, hours after Ressa's arrest.

You know a government is desperate when they arrest a journalist.

President Duterte: FREE @mariaressa NOW.@UNESCO@pressfreedom#MariaRessa#PressFreedom https://t.co/Ot4g3v6s34

— Christiane Amanpour (@camanpour) February 13, 2019

Former United States Secretary of State Madeleine Albright said the Philippine government's act against Ressa, "a friend," must be condemned by the other democracies of the world.

"The arrest of journalist @mariaressa by the Philippine government is outrageous and must be condemned by all democratic nations. I’m proud to call her a friend and to stand with her in defending the principles of a free press," she tweeted Thursday.

The arrest of journalist @mariaressa by the Philippine government is outrageous and must be condemned by all democratic nations. I’m proud to call her a friend and to stand with her in defending the principles of a free press. https://t.co/Hy09UFsARl

— Madeleine Albright (@madeleine) February 13, 2019

In her tweet, Albright shared Washington-based National Democratic Institute's (NDI) condemnation of Ressa's arrest.

"A free press is an essential ingredient in any democracy, and journalists are often the ‘canaries in the coal mine’ when authoritarians seek to consolidate power against the will of the people,” said NDI President Derek Mitchell in the group's statement also posted on Twitter.

“The Duterte government’s latest move to silence the Philippine media should be seen by the international community for what it is: a warning sign that should not go ignored,” he said.

National Bureau of Investigation agents arrested Ressa Wednesday night following her indictment for cyber libel over the complaint of businessman Wilfredo Keng on a Rappler article published in 2012, which the Department of Justice deemed "defamatory."

Ressa said her arrest was part of the administration's continuing harassment over Rappler's critical reporting. The news website is also facing a tax suit, and its incorporation certificate was revoked in 2018 for allegedly violating the constitutional restriction on foreign ownership of mass media.

• READ: 'I shouldn't be detained': Maria Ressa calls on gov't to observe rule of law

The Alliance of Independent Journalists- Indonesia also issued a statement "expressing solidarity and support" for Ressa, Rappler and journalists in the Philippines.

"This arrest was none other than an attempt to silence journalists and media who were critical to the government," it said.

It called on the Philippine government "to respect democracy, protect the freedom of the press by stopping all kinds of intimidation and drop all charges against Maria Ressa."

Kathleen Carroll, board chair of the Committee to Protect Journalists, said she was "outraged" by Ressa's arrest.

"The arrest of Maria Ressa is an outrage. She should be freed immediately and the #Philippines government needs to cease its multi-pronged attack on #Rappler, its talented leader, and its brave staff," she said in a tweet CPJ shared Thursday morning.

United Nations special rapporteur Agnes Callamard, a vocal critic of the Duterte administration, also expressed solidarity with Ressa.

"And another terrible nail in the coffin. #Philippines Maria, I am thinking of you. You can count on me. You can count on us," tweeted Callamard, who is special rapporteur on extrajudicial, summary or arbitrary executions.

And another terrible nail in the coffin. #Philippines Maria, I am thinking of you. You can count on me. You can count on us. #pressfreedom https://t.co/aUbJfV1QsW

— Agnes Callamard (@AgnesCallamard) February 13, 2019

In December, UN special rapporteur on freedom of expression David Kaye had called on the Philippine government to drop cases against Ressa and Rappler, calling the cases "a serious threat against independent and investigative journalism in the Philippines."

The Philippines slipped by 6 notches in the 2018 World Press Freedom Index by watchdog Reporters Without Borders (RSF), ranking 133rd out of 180 countries.

In its report, RSF cited a "growing animosity" towards journalists "openly encouraged" by political leaders.

• 'Growing animosity' vs journos: PH slips in 2018 world press freedom index