The Armed Forces decided on Saturday to deploy units from its second army to maintain stability in Port Said and protect the public facilities, reported the Middle East News Agency.
Eight people were killed during an attempt to break into the prison; two police officers and six civilians.
Port Said Criminal Court sentenced to death 21 defendants accused of involvement in killing 74 people during riots that followed a football match in Port Said last February.
Following the verdict, families of the convicted attempted to break into the Port Said Prison to free their relatives.
Witnesses said that troops guarding the prison fired tear gas canisters at angry protesters to thwart the attempt.