The health of Lee Kuan Yew, who is widely regarded as the founder of modern Singapore, has worsened because of an infection, the government said Tuesday.
Lee was hospitalized on February 5 for severe pneumonia and has since been placed on a ventilator.
"He is on antibiotics," said a statement from the office of his son and current Prime Minister Lee Hsien Loong. "The doctors are closely monitoring his condition."
There appeared to be no increased activity around downtown Singapore General Hospital, where Lee is being treated, but a security guard said Lee's visitors usually entered the building via a private entrance.
In a book published in 2013, Lee had said he felt weaker by the day and that he wanted a quick death.
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.
The Singapore dollar pared gains immediately after news of Lee's worsening health condition.
Lee co-founded the People's Action Party (PAP), which has ruled Singapore since 1959 and led the newly born country when it was separated from Malaysia in 1965. Lee stepped down as prime minister in 1990.
In the last election in 2011, the party won 93 percent of the seats despite its support sliding to around 60 percent of the popular vote. Many voters complained about the high cost of living and a rise in immigration.
Many people in Singapore have been turning to social media sites to express their support for the ailing former leader.
“For all his work and belief for and in us as a nation, we can only pray for his stability of health, and continue to carry on his profound legacy of building a better nation from all he has taught us,” Darius Lim wrote on the prime minister's Facebook page.
Some material for this report came from Reuters.