ISTANBUL (Reuters) - Turkish police fired rounds of teargas to disperse a crowd of several hundred demonstrators rallying in central Istanbul on Tuesday against the death of a protester in the southern province of Hatay earlier in the day, witnesses said.

Dozens of riot police backed by water cannon advanced down a main pedestrian avenue and some fired teargas canisters into side streets as protesters fled after the police blocked their entrance into the city's Taksim Square.

As the police intervention began, the main street was lit up by flashes of light as masked protesters set off fireworks directed at the police.

Ahmet Atakan, 22, died in the early hours of Tuesday in the city of Antakya at a demonstration against police handling of nationwide anti-government protests this summer, but the cause of his death was in dispute.

His death prompted calls for demonstrations across Turkey, including by an umbrella group that was at the heart of the anti-government protests, triggered by plans to redevelop Taksim Square.

The demonstrations have largely cooled since early July but there have been sporadic protests in Istanbul, Ankara and Hatay.

Tensions remain high in Hatay, a province of mixed ethnicities and religions that borders Syria, especially as the United States contemplates military strikes against President Bashar al-Assad over the suspected use of chemical weapons.

(Reporting by Ece Toksabay and Murad Sezer; Writing by Daren Butler; Editing by Alison Williams)