A small bomb exploded in the vicinity of the main presidential palace in the Egyptian capital on Monday, killing a police colonel and wounding three street cleaners, police officials told AFP.
The blast came days after a militant Islamist group warned it had planted bombs near the Ittihadiya palace in east Cairo, and claimed it did not set them off to avoid civilian casualties, Al Arabiya reported.
The attack occured on the day Egypt is preparing for celebrations to mark the anniversary of June 30 protests last year which lead to the ouster of Islamist President Mohammad Mursi.
There is expected to be a high turnout in Cairo's Tahrir Square, where protests were staged last year demanding the "withdrawal of confidence" from then President Mursi.
Last year, a campaign saw mass protests calling for Mursi to step down exactly 12 months after he was inaugurated. The campaign, named Tamarod (Arabic for "rebellion"), accused Mursi of "threatening his own people" and rejected Muslim Brotherhood rule.
The protests led to then then Egyptian army chief Abdel Fattah al-Sisi ousting Mursi and announcing the head of the Supreme Constitutional Court, Adly Mansour, as caretaker leader.
It has been a turbulent year for Egypt which has seen a new constitution and president be installed. Sisi resigned from the army and became a candidate in the presidential elections last month which he won in a landslide vote.
In a statement to the press on Monday, Cairo governor Dr. Mustafa Jalal al-Said has said that security forces will be on high alert throughout the day.
The last time large crowds gathered in the Square was during celebrations on Sisi's inauguration day earlier this month. But the celebrations were mired by a sexual assault on a woman by a mob in the Square.