Former Malaysian Prime Minister Mahathir Mohamad is in hospital after suffering a mild heart attack.
Mahathir Mohamad is still an influential figure in Malaysia
The 81-year-old is reported to be in a stable condition and will remain in hospital in Kuala Lumpur for the next few days.
Dr Mahathir was Malaysia's longest serving prime minister, having spent 22 years in office before his retirement in 2003.
He still wields considerable influence on domestic politics and business.
More recently, he has been in a political scrap with his chosen successor, Prime Minister Abdullah Badawi, whom he accuses of corruption, nepotism and mismanaging the economy.
Dr Mahathir was admitted to the National Heart Institute in the early hours of Thursday, hospital officials said.
"He had a mild heart attack late last night, early this morning," Dr Mahathir's son Mokhzani Mahathir told Reuters news agency.
"He is under observation, the condition is stable. The doctors gave some medication. He is likely to remain in hospital for a few days."
The heart attack happened shortly after Dr Mahathir returned from a trip to New Zealand.
"He had been a travelling a lot ... He had quite a hectic schedule and he ate too much," Mokhzani Mahathir said.
Dr Mahathir, a former medical doctor, underwent heart bypass surgery in 1989 and has been receiving regular check-ups since then.
Although a controversial figure abroad for his barbed comments about the West and scant regard for human rights, at home Dr Mahathir is considered the father of modern Malaysia.
During his time in office, he helped transform Malaysia from a mainly rural economy into an Asian economic tiger.
Despite promising not to interfere when he retired three years ago, Dr Mahathir has launched a series of stinging attacks on his hand-picked successor in recent months.
Analysts say he has been angered by changes introduced by Abdullah Badawi that appear to be partially dismantling his legacy.