US President Barack Obama has cancelled military exercises with Egypt to protest about the killing of hundreds of demonstrators.

During his first public statement since events took a turn for the worse, he has condemned the violence.

Official figures says 525 people died following a violent military assault on two camps of demonstrators in Cairo yesterday.

The U.N. Security Council's scheduled an emergency briefing on the situation in Egypt following the government's deadly crackdown on supporters of ousted President Mohammed Morsi.

President Obama says it's unacceptable that civilians are being killed.