KUALA LUMPUR, Jan 7 — Former prime minister Tun Dr Mahathir Mohamad has been admitted to the National Heart Institute (IJN) in preparation for an unspecified procedure, the hospital said today.

Dr Mahathir, 96, had spent over a week at the IJN last month, during which he underwent a series of tests.

"Tun Dr Mahathir Mohamad today was admitted to IJN for an elective medical procedure.

"Due to the current SOPs, no visitors are allowed to visit Tun Mahathir,” the IJN said.

Dr Mahathir has a history of illnesses relating to his heart. He had his first heart attack in 1989, when he was 64 years old.

Then, in 2006, he had two more heart attacks, and underwent a quadruple bypass surgery a year later.

Prior to last month, the last time Dr Mahathir was hospitalised was on February 10, 2018, also at IJN — due to a chest infection.