Maria Ressa , the editor of Philippine online news website Rappler, has turned herself into the authorities on Monday after a warrant was issued for her arrest.

Last month the government announced it was charging Ressa and Rappler with five counts of tax fraud, charges that Ressa said were trumped up in an attempt to "harass and intimidate" the news organisation, which has been highly critical of president Rodrigo Duterte's administration.

On Sunday night, Ressa confirmed to the Guardian a warrant for her arrest had been issued. On Monday morning, she surrendered to the authorities at Pasig city regional trial court in Manila and posted bail, which was set at 60,000 Philippine pesos (GBP900).

Speaking outside the courthouse after posting bail, Ressa said that "now is certainly not the time to be afraid".

"We need to hold government to account, and part of the reason I'm here is precisely that," she said. "I'm not a criminal but I've been fingerprinted like a criminal. We feel that we did not get due process."

She added: "Frankly, it's a bit shocking to me the lengths government will go to let little Rappler feel its power."

Maria Ressa

The warrant was issued on 28 November but the arrest of Ressa was ordered only on her return to the Philippines on Sunday. She had spent several weeks travelling to receive multiple awards for her work with Rappler , including the 2018 Knight International Journalism award and this year's prestigious Press Freedom award given by the Committee to Protect Journalists.

"I'm going to challenge the process and I'm going to challenge the charges," Ressa said on Sunday, moments after landing in Manila airport. "I will continue to hold the government accountable."

The Department of Justice confirmed last week it was charging Rappler with three counts of failure to file returns, and one count of tax evasion, all charges that Ressa denies. The charges carry heavy fines and jail sentences of up to 10 years.

The move to arrest Ressa is the latest in what many have seen as a direct attack by Duterte's regime on news organisations that have been critical of his government, in particular his war on drugs which has taken an estimated tens of thousands of lives over the past two years.

Rappler was among the main news organisations challenging the extrajudicial killings by the police and subsequently has been the subject of seven government investigations, with their political reporter also banned from the presidential palace.

The National Union of Journalists in the Philippines issued a statement damning the warrant issued for Ressa's arrest. They stated: "Arresting Maria will send a clear signal that the country's democracy is fast receding under a feckless administration that cannot abide criticism and free expression and will go to ridiculous lengths to muzzle all those it does not agree with."