ALEXANDRIA, Egypt, March 25 (Reuters) - Police fired tear gas to disperse hundreds of demonstrators gathered on Tuesday at Alexandria University to protest against mass trials of Muslim Brotherhood members, a Reuters witness said.

The leader of the Brotherhood and 682 others were put on trial earlier in the day in the southern town of Minya on charges including murder, a day after more than 500 other supporters of deposed Islamist president Mohamed Mursi were sentenced to death. (Editing by Michael Georgy and Andrew Heavens)