Myanmar junta extends Aung San Suu Kyi's house arrest
62 year old Suu Kyi has spent more than 12 of the last 18 years in detention and her supporters argue that she must be released or be tried in court rather than this political limbo.
US President George Bush said he was "deeply troubled" by the decision, which comes amid criticism of the generals' response to Cyclone Nargis.
Ms Suu Kyi's party won 1990 elections, but she was denied power by the junta.
Ms Suu Kyi's detention has long been the cause of friction between the junta and the international community.
Her party used the anniversary to denounce the regime's claim that 93% of voters had endorsed a new military-backed constitution at a recent referendum.
It said the vote was a "sham" that was not free or fair, and claimed the authorities "used coercion, intimidated, deceived, misrepresented and used undue influence" to boost the number of "yes" votes.
The party also denounced the regime for holding the referendum so soon after Cyclone Nargis, saying the ruling generals only considered "power politics and self-interest", not public welfare.
Mr Bush called for the release of all political prisoners, and for the military rulers to enter a "genuine dialogue" with pro-democracy and ethnic minority groups.
Previously NowPublic contributor posted on the arrest of Suu Kyi supporters by the police earlier on Monday.