ANKARA, Turkey -- Thousands of pro-secular demonstrators have gathered in the Turkish capital for a march to mark the founding of the republic in defiance of a government ban.

The Republic Day celebrations have in the past few years become a symbol of the divide between the Islamic-leaning government and its opponents who fear the country's secular traditions are in peril.

The government denied authorization for Monday's march citing security reasons and declared the gathering illegal. The march is supported by the main opposition party.

Demonstrators on Monday held Turkish flags and posters of Mustafa Kemal Ataturk who founded the secular republic 89 years ago. They plan to walk from a building housing Turkey's first parliament to Ataturk's mausoleum.

Media reports say police have prevented buses carrying some demonstrators from travelling to Ankara.