Kyrgyzstan's President Almazbek Atambayev has been transferred to Russia for treatment after suffering suspected heart trouble, his office said Friday, several days after he was hospitalised in Istanbul.

Atambayev arrived in Moscow and was admitted to the city's presidential hospital "on the recommendation of specialists", the statement from the presidential administration noted.

Atambayev, 60, was stopping off in Istanbul en route to the United Nations General Assembly in New York when he was hospitalised following complaints of "chest pains", officials said Monday.

Turkish news agencies showed dramatic footage of the Central Asian country's leader lying prone on a stretcher but his office later said his health was "satisfactory" in a statement.

Atambayev has taken time off since the health scare but released a statement Wednesday calling on MPs to pass a law to allow a referendum on controversial constitutional changes to take place in the near future.

Impoverished Kyrgyzstan is commonly viewed as the most democratic country in ex-Soviet Central Asia, an authoritarian former communist region that gained independence from the Soviet Union in 1991.

Atambayev -- viewed as a close ally of Russia -- was elected to power for a single six-year term in 2011 and is due to leave power next year.

But his political opponents, including predecessor Roza Otunbayeva, have raised concerns the changes are an attempt to "usurp power" in a country prone to political upheaval.