"This is worse than before," Soebiandono said, adding that Suharto turned into critical condition since early Sunday as the former leader suffering multiple organ failure.
"This is the most critical condition since Pak (Father) Harto has been hospitalized," said Dr Djoko Rahardjo, another physician. "We are doing our best to help him recover, but all of that depends to God."
The 86-year-old ex-president was rushed to hospital on January 4 with severe heart, lung and kidney problems and suffered multiple organ failure. Since then, his condition has been fluctuating with doctors saying Indonesia's second president's life mostly has been supported by machines.
On Saturday, the former strongman was showing signs of progress as he breathing on his own, using a ventilator only as a backup. Doctors said that the former political strongman would be able to leave hospital soon if his condition continued to show signs of improvement.
Suharto, who runs the world's fourth most-populous country with an iron fist for 32 years, was forced to step down in 1998 amid deadly riots and mass pro-democracy protests that were sparked by the 1997 Asian economic crisis.
Human rights groups accused Suharto of killing hundreds of thousands of people, including up to 500,000 alleged communist sympathizers, in the aftermath of a failed coup attempt that help him rise to power in 1965.
After leaving office he dropped out of public view and avoided criminal trial for massive corruption allegations by citing poor health. Doctors have said two strokes left him with some permanent brain damage.