Ex-premier Dr Mahathir Mohamad was discharged today from the National Heart Institute (IJN), where he had been treated for flu, an official said.

"He was discharged about 4.15 pm because the doctors were happy with his improvements," his aide Sufi Yusoff told AFP . "He went back home."

The 81-year-old Mahathir, who had a mild stroke in November, was taken to the heart centre after he experienced discomfort yesterday, but one of his sons, Mokhzani Mahathir, said he had gone there because his regular physician works there.

"They want to make sure it doesn't turn into a lung infection of any sort. But he's OK. His lungs are OK," Mokhzani said.

"As a precautionary measure they always take him to (the institute). They know him best," he told AFP .

Mokhzani also said his father's heart had recovered from the mild stroke, caused by a blood clot that restricted blood flow in one of his arteries.

Slight discomfort

"Once they removed the blood clot through medication, there was really no problem. It was detected early enough that it had no serious impact," Mokhzani said.

Referring to the flu treatment, Mokhzani said: "Basically, I think he got nervous and he felt discomfort in the chest, and remembering how the last episode panned out, he decided to take precautionary measures."

The ex-premier previously suffered a heart attack in 1989 and had bypass surgery.

Mahathir retired from office in October 2003 after 22 years in power, handing over the reins to Abdullah Ahmad Badawi, whom he has since accused of nepotism and corruption.

He has also seized on the issue of conflict in the Middle East during his retirement, last week launching an unofficial war crimes tribunal to focus on victims of abuse in Iraq, Lebanon and the Palestinian territories.