He was admitted to a private hospital Saturday night.
Azizul Hoque Islamabadi, central organising secretary of Hefazat, told the Dhaka Tribune that Shafi felt sick in the evening.
“The physicians have informed us that he is feeling very weak,” said Islamabadi.
The nonagenarian spiritual leader, also called as Boro Hujur (the eldest scholar) by his followers, has been suffering from various old age complications including high blood pressure and diabetes.
Shah Ahmed Shafi is the rector of Al-Jamiatul Ahlia Darul Ulum Moinul Islam, also known as Hathazari Madrasa.
He is also the chairman of Bangladesh Qawmi Madrasa Education Board.