Around 600 people have been arrested in Turkey's largest city, Istanbul, during a rally commemorating the 30th anniversary of a mass shooting. Authorities allowed a handful of union leaders to lay red carnations at the site of the killings, but rushed in to make arrests as hundreds gathered in Taksim Square.

Police have enforced a strict security clampdown in the centre of the city to prevent violence erupted during May Day rallies which often attract tens of thousands of people. But the increased presence seems only to have stoked tensions. The government will be watching closely to see whether an official May Day march in the city later turns into a protest against the ruling AK Party following a demonstration by up to a million people here on Sunday.