MANILA - Philippine government agents have again arrested the top executive of a news website that President Rodrigo Duterte has targeted for its critical coverage of his bloody drug war.

Maria Ressa, chief executive of online news platform Rappler, was served an arrest warrant early Friday (March 29) morning, shortly after her plane landed at Manila's main airport. She had returned from a business trip in San Francisco.

She was released at around noon Friday after posting bail.

Her arrest stemmed from new charges filed this week accusing her and Rappler's board members of violating the country's anti-dummy law.

The law bars Filipinos from acting as owners of local companies on behalf of foreigners. It imposes limits on how much of Philippine companies foreigners can own. In most cases, foreigners can have, at most, a 40 per cent stake in local firms and properties.

Media companies like Rappler, however, should be 100 per cent Filipino-owned.

Government prosecutors claimed that Ressa and six of Rappler's board members broke the anti-dummy law in 2015 when they granted Omidyar Network, a fund created by eBay founder Pierre Omidyar, the means to exercise control over the news site, or veto powers on company decisions.

Although Omidyar transferred its stake to Ressa and Rappler's board members in 2018, that made them "dummies" for Omidyar, according to prosecutors.

"This is a travesty of justice. I have done nothing wrong. I am not a criminal. I am treated like a criminal," Ressa said in a tweet, as she was being led to a court where she posted bail.

Before leaving San Francisco for Manila, she had tweeted: "Coming home to confront yet another ridiculous criminal case."

Mr Duterte's spokesman Salvador Panelo insisted in a news conference Ressa's arrest followed "due process".

"When Maria was charged, there was a preliminary investigation on that. Then probable cause was determined. Due process has been observed," he said.

In 2018, the Philippines' Securities and Exchange Commission (SEC) had ruled that Rappler violated laws barring foreign ownership and control of local media, and moved to revoke its registration.

An appellate court later ruled that while Omidyar's stake represented "some foreign control", the SEC should have allowed Rappler to correct the error instead of shuttering it, which it said should be a "last resort". The court upheld that ruling on March 11.

Rappler had insisted Omidyar was never given voting rights, and therefore never had a say in its operations.

In a statement, Human Rights Watch said Ressa's arrest "is unprecedented and speaks volumes of the Duterte administration's determination to shut the website down".

"The administration has shown a relentlessness in its persecution of government critics unseen since the time of the Marcos dictatorship," it added.

Senator Francis Pangilinan, head of the opposition Liberal Party, scored "this mob mentality and aggression towards the media".

"The arrest... may be a simple bailable case at hand. But just how law enforcers were carrying it out sends a chilling message to other media outlets and to the public in general of portent of things to come if one gets in the way of the administration," he said.

Mr Duterte has bristled at Rappler's critical coverage of his government. The news site has scrutinised his brutal crackdown on the narcotics trade, challenged the accuracy of his public statements and criticised his foreign policies.

He has banned one of Rappler's senior reporters from covering him, and lashed out at the news platform in several public speeches.

He said in January that Rappler had been "throwing trash and shit all along", adding that its stories were full of innuendo and "pregnant with falsity".

He said he could not care less whether Rappler continued to operate or not, and challenged it to prove that he was behind the SEC's move against it.

He has also threatened several times to block the licence renewal for ABS-CBN, the largest broadcast network in the Philippines.

He has called reporters "spies" and "sons of bitches", and made thinly veiled death threats, warning reporters that they are "not exempted from assassination".

But the President laughed off allegations that he was cracking down on the media.

Ressa was arrested in February over a complaint of cyber libel filed in 2017 by businessman Wilfredo Keng.

Mr Keng was featured in a 2012 Rappler story, updated in 2014, that cited an intelligence report linking him to illegal activities such as human trafficking and drug smuggling.

In another case, Ressa and Rappler were indicted in October 2018 for supposedly attempting to evade taxes by not reporting gains of almost US$3 million (S$4 million) in the company's 2015 tax returns.