Former prime minister Tun Dr Mahathir Mohamad has responded well to treatment since his admission to the National Heart Institute (IJN), Bernama reported.

A statement from Dr Mahathir's office today said he is currently undergoing treatment which involved chest physiotherapy and exercise.

He has been warded at the IJN's general ward.

"The medical team is satisfied with his progress," the statement read.

Doctors have advised that visits be confined to immediate family members.

Dr Mahathir was admitted to the IJN on Monday, following a chest infection. He last received treatment for chest infection in 2010 during a visit to Australia.