Michael Jackson remained in serious but stable condition Thursday after being admitted to the intensive care unit of a Manhattan hospital where he was being treated for a variety of medical problems.

"Mr. Jackson suffered a fainting reaction possibly due to a cardiac arrhythmia with dehydration," his doctors said in a statement distributed at Beth Israel Medical Center North Division.

"Since his emergency admission . . . he has been critically observed in the intensive care unit." The 37-year-old recording star was hospitalized Wednesday after collapsing during a rehearsal for an HBO TV concert special that was to air Sunday but is now postponed.

Ambulance attendants found Jackson semiconscious lying on the side of the rehearsal stage at the Beacon Theater.

On Thursday, Jackson's physicians, Allan Metzger and William Alleyne, said that he was being treated for gastroenteritis, dehydration and electrolyte imbalance, and kidney and liver function.

"His medical team is continually monitoring his condition," the statement said. The doctors said the entertainer would require "several more days" of observation and treatment in the hospital.

While the statement cited a number of ailments, it left room for wide interpretation in the medical community as to the seriousness of Jackson's condition.

"The arrhythmias that patients like this get are usually very trivial," said Dr. David Cannom, medical director of cardiology at Good Samaritan Hospital in Los Angeles and past president of the Greater L.A. Affiliate of the American Heart Assn. "My guess is this is a simple problem and he is going to be all right."

Cannom said he could almost picture what might have happened during Jackson's high-pressure preparations. "That would be a very typical clinical scenario: gastroenteritis, some diarrhea, working out, sweating, not drinking enough--and all of a sudden your blood pressure's 60 and you feel like you're going to pass out. And they call 911. I bet that's what happened. He ought to be fully recovered in a few days."

Jackson was lethargic and mumbling when emergency workers arrived at the theater, where rehearsals were being held for what was to be Jackson's first full-length U.S. concert in almost seven years. The paramedics found that Jackson was so heavily made up they had to lift up his shirt to check his pallor, a medical technician said.

The singer was visited by his wife, Lisa Marie Presley-Jackson, who arrived at the hospital Thursday, and other relatives, including younger sister Janet.

Goldman reported from New York and Crowe from Los Angeles.