Thousands of pro-secular demonstrators gather in the Turkish capital of Ankara on Monday to mark Republic Day.

But this year, the Turkish government declared the rally illegal, citing security concerns.

Clashes broke out as police blocked the road, with the crowd attempting to continue their march to the mausoleum of Mustafa Kemal Ataturk, the highly revered founder of modern Turkey.

Police retaliated with tear gas and water cannon to disperse the large crowds.

But after the scuffles, police allowed the crowd to carry on with their march to Ataturk's mausoleum.

Republic Day marches are usually opposition-led and tend to be anti-government gatherings.

The ruling AK Party in Turkey has moderate Islamic roots but is accused by some secularists of following a religious agenda.