Maradona was receiving treatment at the Cantegrill Clinic after "suffering from a hypertension attack with ventricular arrhythmia, complicated by the fact he already had high blood pressure," said Dr Frank Torres.
Maradona's manager Guill-ermo Coppola denied reports that his condition had been brought on by drug addiction or an overdose.
"Everyone knows that Mara-dona has hypertension," Coppo-la, who was acquitted last year of cocaine possession, told the Radio Mitre radio station.
"It's already happened to him more than once -- in Chile during a television programme and then when playing football in Buenos Aires, but there were no indications that drugs had anything to do with it," he added.
"There was no ambulance, there was no coma, there were no police," he said," blasting what he called sensational press reports of Maradona's ailment.
Torres said the 39-year-old Maradona was admitted to the clinic's intensive care unit on Tuesday afternoon.
Maradona, who all but singlehandedly won the 1986 World Cup for Argentina over Germany and then led them to the 1990 final where the Germans gained revenge, was accompanied to the hospital by his wife Claudia Villafane and Coppola with whom he had been on holiday.
"He is under observation and no complications are expected meaning he should only have a short stay in the clinic," Torres added.
When asked if the problems were brought about by a drug overdose, Torres refused to confirm or deny, answering only: "The hypertension problems could have many different causes."
Maradona has had repeated drug problems and has had rehabilitation several times. He was even thrown out of the 1994 World Cup for failing a drugs test and had a drugs ban while playing for Napoli in Italy.
He had been on holiday at the expensive holiday resort of Punte del Este where he spent the New Year.
Maradona, who courted controversy throughout a tempestuous career with Boca Juniors, before European stardom with Barcelona and Napoli, was recently voted Argentine spor-tsman of the 20th century.
He retired from football in 1997.
Argentine President Fernando de la Rua said he hoped Maradona would make a speedy recovery.
"He has given so much happiness to everyone," he said.
Among those to visit Maradona in the clinic were former president Carlos Menem and Uruguayan international Enzo Francescoli.
"I feel reassured because Diego is perfectly all right," Menem said.