Diego Maradona is heavily sedated in intensive care following a crisis of hypertension or high blood pressure, his doctors said on Sunday after the Argentine soccer great was taken ill and admitted to a clinic.

Maradona, who has long been in therapy to battle a drug addiction that has left him a bloated shadow of his former self, was breathing with the help of a respirator and his condition was "reserved", the doctors said in a statement.

"Diego Armando Maradona has been admitted to intensive care... because of a crisis of hypertension related to miocardium," said the statement.

"He also had respiratory difficulties and so is aided by a respirator, as a result of which he is permanently sedated."

"His initial haemodynamic reaction is moderately favourable," the statement added.

Maradona's family doctor Alfredo Cahe refused to comment on reports that the former soccer star had taken a cocaine overdose, saying an update on his condition would be issued on Monday.

Family, friends and well-wishers flooded to the Suizo-Argentina clinic on Sunday evening as news of the 43-year-old's condition spread.

One teary-eyed fan held aloft a photograph of Maradona in his soccer-playing prime. A banner read "Diego, Argentina loves you", while passing cars honked their horns.

Television channel Todo Noticias said Maradona had fallen ill after taking a drug overdose but gave no source for the report.

Maradona had earlier attended a soccer game at his former club Boca Junior's stadium in the Argentine capital before being taken ill and whisked to the clinic in an ambulance.

Maradona is regarded as one of the finest players to have graced the game, leading Argentina to World Cup victory in 1986.

His supporters are so fanatical that some 20,000 people as far afield as Vietnam and Iceland have become members of the 'Church of Maradona'.

He has also been honoured with a musical about the ups and downs of his turbulent rags-to-riches life.

However, drug use off the pitch marred Maradona's career, and he is often barely intelligible in interviews screened on local television.