OSLO, Norway — Myanmar opposition leader Aung San Suu Kyi declared Saturday that the Nobel Peace Prize she won while under house arrest 21 years ago helped to shatter her sense of isolation and ensured that the world would demand democracy in her military-controlled homeland.

Suu Kyi received two standing ovations inside Oslo’s city hall as she gave her long-delayed acceptance speech to the Norwegian Nobel Committee in front of Norway’s King Harald, Queen Sonja and about 600 dignitaries. The 66-year-old champion of political freedom praised the power of her 1991 Nobel honor both for saving her from the depths of personal despair and shining an enduring spotlight on injustices in Myanmar.

“Often during my days of house arrest, it felt as though I were no longer a part of the real world,” she said. “There was the house which was my world. There was the world of others who also were not free but who were together in prison as a community. And there was the world of the free. Each one was a different planet pursuing its own separate course in an indifferent universe.

“What the Nobel Peace Prize did was to draw me once again into the world of other human beings, outside the isolated area in which I lived, to restore a sense of reality to me. … And what was more important, the Nobel Prize had drawn the attention of the world to the struggle for democracy and human rights in Burma. We were not going to be forgotten,” she said.

Suu Kyi, who since winning freedom in 2010 has led her National League for Democracy party into opposition in Myanmar’s parliament, offered cautious support for the first tentative steps toward democratic reform in her country.

But she said progress would depend both on maintaining foreign pressure on the army-backed government — and on carefully managing the ethnic tensions threatening to tear apart the country.

“If I advocate cautious optimism, it is not because I do not have faith in the future, but because I do not want to encourage blind faith. Without faith in the future, without the conviction that democratic values and fundamental human rights are not only necessary but possible for our society, our movement could not have been sustained throughout the destroying years,” she said, referring to the past two decades since Myanmar’s military leaders rejected her party’s overwhelming triumph in 1990 elections, one year after Suu Kyi’s own imprisonment.