By Tatyana Kekic in Belgrade Tens of thousands of people gathered in the southern Serbian city of Niš on March 1 to mark the fourth month since a deadly railway station disaster, in what has become the largest and most significant challenge to President Aleksandar Vucic’s decade-long rule.

Tens of thousands of people flocked to the southern Serbian town of Nis on Saturday (March 1) to commemorate victims of a railway station disaster and take part in a series of student-led protests that have become the biggest threat yet to President Aleksandar Vucic's grip on power.