Lawyers hit out at a variety of tactics used by police to obstruct their profession.
Netizens say 'sensitive' keywords are blocked and any content about the 25th anniversary is quickly deleted.
A top rights lawyer and a Beijing film professor remain in police custody on public order charges.
Killings and detentions continue in ethnic areas, rights groups say.
Chinese society has been carrying a 'deep wound' in the 25 years since the crackdown, a scholar says.
But Beijing refuses to respond to the Philippine filing.
Mainland Chinese join the city's annual vigil as organizers report record turnout.
Police patrol university campuses, once the heart of the 1989 student-led democracy movement.
Lee Teng-hui says that the crackdown undermined stability in China, rather than reinforced it.
Bao Tong is among several taken by police ahead of the Tiananmen anniversary.
An activist who announced an online essay competition on the 1989 student movement is held on public order charges.
A young girl sings the song in Cantonese ahead of a ballot on universal suffrage.
Authorities have detained at least eight lawyers on public order charges in recent weeks.