Famed Brazilian architect Oscar Niemeyer is in critical condition with worsening kidney function, a clinic where he has been hospitalized for two weeks said Saturday.

Niemeyer, who turns 105 next month, is "lucid and getting respiratory physiotherapy," the Hospital Samaritano in Rio told AFP in a text message.

He has been hospitalized at the clinic since November 2 after his kidneys took a hit from dehydration and the flu.

On Friday, Niemeyer suffered gastrointestinal bleeding that was stemmed by physicians.

The architect's "renal function has deteriorated and he requires further care," the hospital said.

He underwent an 11-day hospital stay for similar problems in October. In May, he was hospitalized for both pneumonia and dehydration.

Niemeyer is best known for having designed the Brazilian capital Brasilia in 1960, among 600 other works around the world over the course of a storied career.

A pioneer in the use of reinforced concrete to produce soaring, curvaceous forms, he currently has some 20 projects underway in several countries.

Niemeyer won the Pritzker Prize, considered the Nobel for architecture, in 1988.

His only daughter, Anna Maria Niemeyer, died of emphysema in June at the age of 82.