Some of the tanks are located in the square of Rab'a al- Adawiyah in east Cairo where Islamists intend to stage massive protests on Friday in support of President Mursi, who would complete his one year in office this weekend.
Meanwhile, clashes between supporters and opponents of President Mursi today left at least one person dead and several others injured.
They want to take to the street on June 30, the day Mursi would complete a year in power.
But the Islamists said they would fill the squares as of June 28 to abort the planned protests by opposition.
Officials said the military has been coordinating with Mursi's government in the run-up to the protests, but activists say they are looking to the army for protection from hard-line government supporters.