Authorities in the Egyptian province of Suez, northeast of Cairo, beefed up security around churches following a minor explosion near a local church late Saturday, security sources said.
Three passersby suffered slight injuries in the Saturday explosion, which took place a few meters away from the Latin Church in Suez. Policemen cordoned off the area and are searching for suspects.
Suez Deputy Security Chief Gen. Hassan Eid told journalists earlier that the explosives experts said the blast was caused by firecrackers with the aim of causing panic in the area.
Meanwhile, the National Alliance for the Defense of Legitimacy, the main support block for ousted President Mohamed Morsi, expressed fears that the authorities may use the alleged explosion to crack down on opposition in Suez.
Egyptian authorities have raided several areas across Egypt, including the village of Dalga, in the southern province of Minya, and the village of Kerdasa, in Giza, to eradicate what they call "terrorism" and "criminal strongholds".
Tensions have risen in Egypt since the powerful army ousted Morsi, the country's first freely-elected head of state, on July 3.