President Iajuddin Ahmed, 75, who was suffering from heart problems, arrived at Mount Elizabeth Hospital by ambulance and was seen lying on a stretcher as medics took him inside the building.
Earlier, in Dhaka, Press Secretary Mukhlesur Rahman Chowdhury said the president was admitted to Dhaka's Combined Military Hospital on Tuesday with complaints of chest pain.
He said Ahmed's condition on Wednesday was "stable," but a five-member medical team advised flying him to Singapore for treatment. He was flown by air ambulance.
The president has a history of heart problems, Chowdhury said, without providing further details, the AP reports.
Ahmed's wife, Anwara Begum, son Imtiaz, his personal physician and security personnel were traveling with him, Chowdhury said.
Ahmed is a titular head in Bangladesh, which is a parliamentary democracy with executive powers held by the prime minister.
Under the country's constitution, speaker of the national parliament, Zamiruddin Sircar, will be acting president during Ahmed's absence. Sircar, who was visiting London, was on his way back to Dhaka, Deputy Speaker Akhtar Hamid Siddique said.
Prime Minister Khaleda Zia, who was on a two-day official trip to the United Arab Emirates, was also due to return home later Wednesday.
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