SINGAPORE - Former Prime Minister Lee Kuan Yew's health weakened further on Sunday, according to a statement from the Prime Minister's Office (PMO).

Mr Lee, 91, took a turn for the worse on Tuesday and has been critically ill since then. The PMO said yesterday that his condition had worsened further.

He has been hospitalised at the Singapore General Hospital (SGH) since Feb 5 with severe pneumonia.

Prime Minister Lee Hsien Loong and his wife Madam Ho Ching visited the elder Mr Lee at SGH on Sunday morning. PM Lee also met well-wishers who have been visiting SGH to leave cards and gifts for Mr Lee Kuan Yew at a designated area outside the hospital's Block 7.

Timeline:

FEB 5: Mr Lee Kuan Yew is hospitalised at the Singapore General Hospital for severe pneumonia.

Feb 21: The Prime Minister's Office (PMO) issues a statement to announce Mr Lee's hospitalisation. It says his condition has stabilised and he is on mechanical ventilation.

Feb 26: Mr Lee's doctors restart him on antibiotics.

Feb 28: Mr Lee's condition improves slightly. He remains sedated and on mechanical ventilation, and is continuing with his antibiotics, PMO says in an update.

March 6: PMO says Mr Lee's condition remains largely unchanged from the last update.

March 13: Mr Lee's condition remains largely unchanged, PMO says.

March 17: Mr Lee's condition worsens due to an infection.

March 18: Mr Lee remains critically ill in the intensive care unit and his condition has deteriorated further, PMO says.

March 19: Mr Lee remains critically ill in the intensive care unit.

March 20: Mr Lee remains critically ill. Prime Minister Lee Hsien Loong would like to thank the public for their support and good wishes, PMO says.

March 21: Mr Lee's condition has worsened, PMO says in a one-line statement.

March 22: Mr Lee's condition has weakened further, says PMO.