An Egyptian police officer was killed on Saturday while attempting to make safe a bomb placed near a Cairo church only two days before 7 January, when Orthodox Christians celebrate Christmas.
Two policemen and an onlooker were injured when one of the two devices found detonated on a rooftop in an eastern suburb of the city.
It is likely the death toll would have been much higher had the bomb exploded as Christians attended Christmas services in the following days.
Official sources said security patrols were being stepped up outside churches and other places of worship ahead of Christmas celebrations.
Muslim-majority Egypt has a substantial Christian minority, which is one of the oldest Christian communities in the world, dating back to the first century, pre-dating Islam by almost 600 years.