Israeli forces bombed the historic al-Omari Mosque in the northern Gaza City of Jabaliya on Saturday morning.
The mosque, which is believed to have stood on the same site since 647 AD, was almost completely destroyed in the bombing.
The portico and minaret dated back to the medieval Mamluk period, or at least 500 years.
The mosque stood at the center of Jabaliya and was known as the "Great Mosque" by local residents.
Israel said that their forces had bombed five mosques over night, claiming that "weapons caches and Hamas command and training facilities" were concealed within them.
The muezzin whose job was to recite the call to prayer from the mosque's minaret was also killed on Saturday in another strike on the mosque. His name was Daoud Zakariya Suleiman.
More than 10 mosques have been completely destroyed in addition to 80 mosques and two churches that have been partially destroyed in the 26-day assault, according to PLO figures.
(AFP Mohammed Abed)