Maria Ressa, a journalist who runs a Philippine news website known for its tough scrutiny of President Rodrigo Duterte, pleaded not guilty on Wednesday to tax evasion charges, saying the case was politically motivated to harass and intimidate.

Ressa (above), a Time Magazine Person of the Year in 2018 for fighting media intimidation, is facing several government lawsuits that have caused international concern about harassment of journalists in the Philippines, a country long seen as a standard-bearer for press freedom in Asia.

Ressa, 56, who is chief executive of the news site Rappler, was convicted of libel last month and sentenced to up to six years in prison, a ruling widely seen as...