The health of former prime minister Dr Mahathir Mohamad is steadily improving after a heart attack but he will stay in hospital for further care, a statement from the hospital said today.

The National Heart Institute said Mahathir has been transferred out of the cardiac care unit to a regular ward after doctors were happy with his progress.

"He was transferred... after doctors were satisfied at his steady rate of positive response to treatment and medication," the institute said.

"Mahathir is expected to continue to be warded... to allow doctors to monitor his condition and to start cardiac rehabilitation," it said.

Breathing difficulties

Mahathir was admitted after suffering breathing difficulties, which doctors said last Thursday were due to lung congestion caused by a heart attack - the fourth of such attacks.

Mahathir, 81, previously suffered a heart attack in 1989 and had bypass surgery. He also had a mild stroke in November last year, caused by a clot that restricted blood flow in one of his arteries.

Mahathir on Friday was quoted by the state Bernama news agency as saying that he was feeling much better but he acknowledged that he would have to ease up on his schedule on doctors' advice.