Speaking in Berlin to accept a human rights award, she said the country formerly called Burma still needs a democratic constitution, true national reconciliation and a change of mindset among its ex-military rulers.
She urged the world to keep a close eye on the government and to ask: "Does it want to go toward a truly democratic union or does it want to go towards an authoritarian state disguised in democratic garb?"
The former political prisoner has entered parliament, and her National League for Democracy (NLD) plans to contest elections next year, hoping to repeat a sweeping 1990 victory that was ignored by the former junta.
However, her desire to seek the presidency remains blocked by a clause specifically designed for her, which bars anyone with a foreign spouse or children from taking the position. Her late husband was a British national.
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"Unless we change the constitution ... So-called democratic reform in Burma will be no more than window-dressing," she said.
Suu Kyi was receiving the Willy Brandt Award -- the latest in a long line of human rights awards she has picked up since being permitted to travel again in 2012.
However, her reputation has been tarnished over the past 18 months as a result of her failure to comment on brutal sectarian violence targeting Muslims in Myanmar, as well as continued military attacks against ethnic minority rebels.
Thanking her international supporters for backing the cause of freedom, she cautioned that "Burma is not yet a democracy. We have been given the chance to build a democratic society, we have not yet built one.