Egyptian police defused two bombs at Cairo International Airport overnight, security officials said.
And an explosion in central Cairo frightened passers-by but no-one was injured.
Officials said the airport bombs - one planted in the arrivals hall of the terminal hosting EgyptAir and the other near a police patrol location - looked to be controlled remotely by mobile phone.
This morning, officials said a bomb planted inside an electrical box in central Cairo went off, causing alarm but no injuries.
Egypt has been gripped by turmoil since the military toppled Islamist president Mohammed Morsi in 2013. The country has faced attacks ranging from suicide bombings to near-daily small blasts from home-made bombs.