German police remove protestors who are blocking a street at a demonstration during the G20 summit in Hamburg, Germany, July 7, 2017. REUTERS/Pawel Kopczynski

HAMBURG, Germany (Reuters) - German Finance Minister Wolfgang Schaeuble canceled an event with school pupils on the sidelines of the G20 summit in Hamburg on Friday due to the security situation in the city, organizers said.

On Thursday dozens of police were injured in clashes with protesters before the summit started, with riot police firing water cannons at around a thousand black-clad protesters who hurled bottles.

Schaeuble had been due to talk to school pupils from various countries at the ‘G20 Global Classroom’ event.