A prominent Thai editor facing a 20-year prison term on charges related to website criticism of Thailand's monarchy says she did everything she could to keep her site free of comments seen by authorities as defaming the country's revered king.

Editor Chiranuch Premchiaporn testified in a criminal court Wednesday in Bangkok, saying she immediately blocked comments deemed as improper by the Information and Communication Technology ministry.

The 44-year-old editor was charged in 2008 with allowing defamation of royalty, and has since drawn widespread support from local and foreign observers, including Western diplomats and numerous journalists. Human Rights Watch last week awarded her and several dozen other Southeast Asian journalists its prestigious Hellman-Hammett award for their work in furthering free speech.

Chiranuch's forum was closed in July 2010, as the government pressed its crackdown on commentators, following deadly anti-government street protests that gripped the capital weeks earlier.

Analysts say the website was bombarded by tens of thousands of comments before, during and after the rioting, and that a small fraction of the remarks were openly critical of King Bhumibol Adulyadej. The 83-year-old king is the world's longest-reigning monarch and is revered as a God-like figure by many Thais.

But observers say the non-profit website did not have the staff to monitor inappropriate comments on a continual basis. On Tuesday, site founder Jon Ungpakorn testified that he suspects the site was targeted with inappropriate comments in a bid to destroy it.