A small bomb exploded near the Al-Qobba presidential palace in Cairo on Thursday morning, injuring a woman, Al-Ahram Arabic news website reported.
The explosion targeted traffic police stationed under the Al-Qobba Bridge adjacent to the palace in Hadayeq Al-Qobba.
A police officer discovered the device but the explosion occurred before precautions were taken and prior to the arrival of explosives experts, a security source told Al-Ahram.
Recently a similar bomb exploded outside Cairo University, injuring 11.
Al-Qobba presidential palace is mostly reserved for ceremonial occasions. The president's main offices are at the Ittihadiya palace.
A series of explosions killed two policemen at the Ittihadiya presidential palace on 30 June.
Since the ouster of Islamist president Mohamed Morsi in July 2013, militant attacks against security forces in Sinai have expanded into Cairo and the Nile Delta. Civilians have also been caught up in the violence.