Concerns grew about the 80-year-old Pele's health after local media reported he had returned to the ICU he had left earlier this week after removing a tumour from his colon.

Sao Paulo's Albert Einstein hospital said in a statement Pele had "presented a brief respiratory instability" and was admitted to an ICU as a "preventive measure."

After he was stabilised, the statement added he had been moved to "semi-intensive care" and was now "stable from a cardiovascular and respiratory point of view."

Seeking to assuage people's fears about the health of the soccer legend whom many consider to be the greatest player in history, Pele's daughter, Kely Nascimento, said on Instagram her father was doing well.

"He is recovering well and within normal range. I promise!" she said on Friday.

The former Santos, Brazil and New York Cosmos legend had a colon tumour removed earlier this month and was transferred out of the ICU on Tuesday.

However, ESPN Brasil and Sao Paulo's two biggest newspapers reported on Friday he was readmitted to the intensive care unit in the city's Albert Einstein Hospital after suffering from acid reflux.

"Yesterday, he was tired and took a little step back," Pele's daughter wrote, without directly citing the reports. "Today he took two steps forward!"

She also posted on Instagram a photo she said "was taken just now" of the three-time World Cup winner wearing a black vest and smiling for the camera.

After he was transferred out of the ICU on Tuesday, Pele had posted a smiling image on Instagram with the message he was ready for "90 minutes, plus extra time."

He retired from the game in 1977, and his health has been a source of concern to family and fans in recent years.

He has suffered from hip problems for years and cannot walk unaided. In 2014 he spent some time in the ICU due to a severe urinary tract infection.

Last year, Pele's son said his father suffered from bouts of depression, something the star later denied.

His public appearances were already being cut before the COVID-19 pandemic and since then he has made few forays outside his house near Santos.

Australian Associated Press