Brazilian soccer legend Pele smiles during a news conference in Hong Kong in this March 7, 2011 file photo. [Photo/Agencies]

SAO PAULO - Retired Brazilian soccer great Pele is in the intensive care unit in a Sao Paulo hospital where he is being treated for a urinary tract infection, but his condition is improving, the hospital said on Thursday.

The Albert Einstein Hospital said Pele, 74, was receiving renal support treatment, which helps kidneys to filter waste products from the blood, after he had an operation to remove kidney stones earlier this month.

A series of tweets in English from the former player's account aimed to calm concerns over his health. One read: "Want to let you know I am doing fine."

Pele's manager, Paul Kemsley, said in a statement: "He is expected to make a quick and full recovery from a minor infection caused by his recent successful surgery."

Earlier on Thursday, Pele was moved to a special care unit at the hospital, suffering what the hospital called "clinical instability." It did not provide details.

After that move, Jose Fornos Rodrigues, the former player's personal aide, said that Pele had been moved primarily to protect his privacy.

"He was uncomfortable with so many people coming. It'll be quieter now," Rodrigues said.

Pele was discharged from the same hospital on Nov. 13 after the kidney stones surgery.

Often called the greatest soccer player in history, Pele has suffered a long list of health problems in the past decade, including emergency eye surgery for a detached retina and a hip replacement.