Singapore’s first prime minister Lee Kuan Yew, one of the towering figures of post-colonial Asian politics, died Monday in hospital, the government said.

Lee’s son, Prime Minister Lee Hsien Loong, said in a statement that he is “deeply grieved to announce the passing of Mr. Lee Kuan Yew, the founding Prime Minister of Singapore.”

“Mr. Lee passed away peacefully at the Singapore General Hospital today at 3.18 am,” the statement said. He was 91.

Lee had been in hospital since February 5 with severe pneumonia and was on life support. Last week the government said his condition had worsened.

Lee was prime minister from 1959, when colonial ruler Britain granted Singapore self-rule, to 1990. He led Singapore to independence in 1965 after a brief and stormy union with Malaysia.

His death is likely to cast a pall over preparations for the city-state’s 50th anniversary of independence on August 9.