A statement from the Minister Mentor's Office said Mrs Lee, 87, suffered sudden weakness on her left side and slurring of speech around noon on Monday.
She was then taken to the National Neuroscience Institute for an urgent brain scan. The results revealed massive right intra-cerebral haemorrhage, and Mrs Lee was subsequently admitted to the NCU.
The haemorrhage stabilised after two days of close monitoring and treatment. She was then transferred to the general ward on Wednesday.
Mrs Lee currently remains in serious condition although she is able to recognise immediate family members. - CNA/ac