Doctors carried out tests including a CAT scan on the 78-year-old retired five-star general and said his condition had improved since Tuesday.
Sudjono Martoatmodjo, the director of Pertamina Hospital, said Suharto had been scheduled to undergo a yearly checkup, but on Tuesday complained of a headache.
Â"He agreed to go to hospital and after being examined, the doctors found that he had suffered a mild stroke,Â" Sudjono said.
Â"There is a problem with blood vessels in his brain, but he can still talk and we hope that he will improve today.Â"
Earlier, sources at the hospital had said Suharto was initially thought to have suffered a heart attack.
The hospital said it would not perform surgery on the former leader.
Â"There is no need for an operation because an operation is only needed for a heavy stroke and this is not. God willing, he can fully recover within one or two weeks,Â" Martoatmodjo said Wednesday. Â"The possibility of recovery from a light stroke is more than 50 percent.Â"
The hospital said SuhartoÂ's stroke was non-bleeding and attributed the likely cause to old age.
Suharto lawyer Juan Felix Tampubolon said Suharto was able to sit up in bed. Only close relatives were allowed to visit.
The Jakarta Post quoted sources close to Suharto's family as saying he collapsed in his bathroom at his residence in central Jakarta.
Suharto was forced to step down last year amid riots and protests against his authoritarian reign and mishandling of Indonesia's worst economic crisis in a generation.
Long criticized for his human rights record and undemocratic ways, Suharto has denied allegations that he misused his power to enrich himself, his family and friends.
Since his resignation, he has led a reclusive life and has rarely talked publicly.
Meanwhile, Indonesian Justice Minister Muladi said Wednesday that an official probe into SuhartoÂ's questionably attained wealth could be affected by his poor health.
Â"A person must be physically and spiritually healthy in order to undergo a legal investigation. Those conditions have to exist,Â" Muladi told reporters.
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