Aung San Suu Kyi has been held by the military government since May 2003 after an assassination attempt in northern Burma.
The extension of her detention comes a month after the appointment of the man behind the attack, General Soe Win, as prime minister.
Recently the regime announced plans to release up to 9,000 prisoners, but only a handful are classified as political detainees.
Observers say that announcement was timed to ease pressure on the military in the lead up to the ASEAN leaders summit currently under way in Laos.
In line with its policy of non-interference in the affairs of member states, the ASEAN summit's final communique makes no mention of the lack of political reform in Burma.
By In Solidarity 30 November 04
