Former prime minister Dr Mahathir Mohamad is still receiving treatment at the National Heart Institute (IJN) in Kuala Lumpur after being admitted for a chest infection last night.

Dr Mahathir has been placed under medical observation for a few days until his health returns to normal, said an IJN spokesperson.

The IJN Corporate Communications Department said in a statement yesterday that Dr Mahathir, 91, was placed in the general ward and visitors were restricted to family members only on the advice of the medical team.

In 1989, he suffered heart problems and underwent coronary bypass surgery at the IJN.

He underwent heart bypass surgery a second time in 2007.

In 2013, Dr Mahathir was admitted for 10 days to treat a chest infection.

- Bernama