Tun Dr Mahathir Mohamad has been admitted to the National Heart Institute (IJN) for a chest infection, following a bout of coughing.
The institute, which made the announcement in a press statement today, said that the Parti Pribumi Bersatu Malaysia (PPBM) chairman was admitted last night and is currently receiving treatment in the general ward.
Mahathir, 92, is expected to be at the facility for several days for treatment and observation.
The institute stressed that visits are restricted to close family members.
Mahathir reportedly missed a political event in Bentong, Pahang, yesterday.
The former prime minister has a history of heart complications and was most recently admitted to the IJN in 2016, also for a chest infection.
He first suffered a heart attack in 1989 and underwent a bypass operation then.
He subsequently experienced several more cardiac arrests and received a second bypass in 2007.