CAIRO, Dec 12 (Reuters) - Egyptian riot police fired tear gas and water cannon to disperse hundreds of pro-Islamist protesters demonstrating near the headquarters of the ministry of defence in Cairo on Thursday, security sources said.

Egypt has been witnessing almost daily protests by supporters of elected Islamist president Mohamed Mursi since the army removed him in July after mass protests against his rule.

Mursi's removal opened the bloodiest chapter in Egypt's modern history. Security forces have since killed hundreds of his supporters, while some 200 soldiers and policemen have died, many in attacks by Islamist militants in the Sinai peninsula, bordering Israel and the Palestinian Gaza strip.

Students supporting Mursi have been staging daily protests for months inside and outside their universities.

Last month, Egypt's army-installed interim government issued a law that banned protests near or originating from places of worship, and made it compulsory to seek Interior Ministry permission to hold a demonstration.

Since the law was passed, hundreds of Brotherhood protesters and other liberal activists have been arrested for demonstrating without police permission. (Reporting by Yasmine Saleh; Editing by Mark Trevelyan)