Asif Ali Zardari
had a "mild" stroke that caused bleeding in the brain and facial paralysis before he was flown to Dubai for treatment, a media report said on Friday.
However, the President was stable and out of danger as the stroke and internal bleeding were not "life threatening", The News daily quoted its sources as saying.
Zardari would require "some treatment, including speech therapy, to resume his normal life", said the report in the daily known for its strident criticism of the President.
Zardari is "likely to be flown to London for detailed treatment", the daily quoted a source as saying.
Zardari "collapsed in the Presidency" on Tuesday because of the stroke, the source claimed after official denials that Zardari had not had a heart attack.
The presidential spokesman had said on Thursday that Zardari's condition was stable and that he would undergo more medical tests in Dubai.
The spokesman further said the President had been moved from the intensive care unit to a normal hospital room.
Zardari abruptly travelled to Dubai on Tuesday to undergo tests for what officials have described as a previously diagnosed "cardiovascular condition".
His sudden departure fuelled speculation that he was on the verge of resigning on grounds of "ill health" due to growing pressure on him because of the "Memogate" scandal.
The News claimed one of its sources had quoted a presidential aide while another source had got the information from one of the doctors who attended and examined the President.
Zardari is a high blood pressure patient and takes blood thinners, the report said.
"Such patients at times do experience a stroke, which in the case of the President was mild. In certain cases, it becomes fatal," the report added.
It has been widely reported that Zardari has had two or three stents implanted in his heart in the past to open blocked arteries.
Federal minister Mustafa Khokhar had told sections of the media on Wednesday that Zardari had a minor heart attack and had undergone an operation in Dubai.
However, he has been incommunicado since then and has not said anything further on the matter.