President Bush said he was "deeply troubled" by the extension but emphasized that the United States would continue to provide aid for Burma's cyclone survivors.
British Foreign Secretary David Milliband said he was "was saddened, if not surprised," by the decision to keep her detained.
"While our immediate focus is on relieving the suffering caused by the recent cyclone, restoration of democracy in Burma is still vital for that country's long-term future," Milliband said.
The extension of Suu Kyi's detention came as Burma, renamed Myanmar by the junta, was still fending off worldwide criticism for its inadequate aid effort after Cyclone Nargis.
The storm left an estimated 2.4 million people in desperate need of food, shelter, and medical care, according to the United Nations. The government says the deluge killed 78,000 people and left 56,000 missing.
"International aid workers are starting to move to the delta," Richard Horsey, a spokesman for the UN humanitarian effort, said yesterday. Helicopters also began shuttling high-energy biscuits and ready-to-eat meals into the hardest hit area yesterday, he said in Bangkok.
Burma's leaders are leery of foreign aid workers and international agencies because they fear that an influx of outsiders could undermine their control. The junta is also hesitant to have its people see aid coming directly from countries such as the United States, which it has long treated as a hostile power seeking to invade or colonize.
But the Suu Kyi, daughter of the country's martyred independence leader, General Aung San, has long been regarded by the generals as the biggest threat to their power.
Her National League for Democracy party is the country's largest legal opposition group, and it retains the loyalty of millions of citizens despite two decades of repression.
The party won the most seats in 1990 elections, but the military refused to convene parliament. Instead, it harassed and arrested members of the party, setting a pattern that still stands.
Yesterday was the anniversary of the abortive election victory, and about 200 members attended a ceremony at party headquarters.
