Former Malaysian Prime Minister Mahathir Mohamad, 96, was admitted to hospital Thursday and will undergo a full medical check-up, the medical facility said.
The National Heart Institute said Mahathir arrived at 7:00 pm (1100 GMT) and is expected to stay there for the next few days.
Mahathir has had heart problems in the past, suffering several heart attacks and undergoing bypass surgery.
He has been one of Malaysia's most dominant political figures in recent decades, serving twice as prime minister for a total of 24 years.
His first stint was from 1981 to 2003, then he made a comeback and returned as premier in 2018 at the age of 92 at the head of a reformist coalition.
But that administration collapsed in 2020 due to infighting.