Updated

A homemade bomb has exploded near Bogota's bull ring where police and animal rights activists have clashed in recent weeks.

Media reports said as many as 20 people had to be evacuated to local hospitals with injuries although authorities had yet to provide an official count.

The explosion a few hours before Sunday's scheduled bullfight shattered glass windows in nearby apartment buildings.

Police last month fired tear gas and made scores of arrests to control mostly youth demonstrators protesting the return of bullfighting to Colombia's capital for the first time in four years.