KUALA LUMPUR (Kyodo) -- Former Malaysian Prime Minister Mahathir Mohamad, who turned 99 in July, has been admitted to the hospital for a respiratory tract infection after a bout of coughing, his aide said Wednesday.

The country's longest-serving premier is expected to stay in the hospital for around 10 days, the aide said. Mahathir, who served as Malaysia's prime minister twice, first between 1981 and 2003 and again from 2018 to 2020, was hospitalized Tuesday evening.

As he has a heart condition, Mahathir has been in and out of the hospital in recent years.