Lee, the founding father of modern Singapore, has been in hospital with severe pneumonia since February 5. He turned 91 last September.
"Lee Kuan Yew's condition has worsened," a statement from the prime minister's office said on Saturday, a day after the government had said Lee remained critically ill.  
Singapore residents have been leaving flowers, cards and other gifts at the Singapore General Hospital to show support for Lee.
Brenda Chua Jock Suan, 63, a retiree, has been visiting the hospital every day to offer prayers, and encouraged her middle-aged children to do the same.
"I do it because I don't want him to suffer," an emotional Chua said in Mandarin. "I don't buy flowers or cards, but I just hope that my prayers will make things easier for him," she said.
Lee, one of the predominant political figures in modern Asian history, is widely credited with transforming Singapore from a British colonial outpost into a financial powerhouse with one of the highest per capita incomes in the world.
Although he has receded from the public and political scene, his health is watched closely as he is still seen as an influential figure for the current government. His son, Lee Hsien Loong, has been Prime Minister since 2004.
"Well, life still goes on," said Singaporean Tan Kim Lee when asked about the future of Singapore without Lee Kuan Yew.
"Singapore is not run by one man, that's for sure. So we have a good government team in place so I guess life will be normal, except without Mr. Lee," he added.

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