A small bomb killed a street cleaner in the Egyptian capital Cairo late Saturday, a security official said.
The blast occurred near a tram track in the working class neighbourhood of Mattariya, a stronghold of supporters of ousted Islamist president Mohamed Morsi.
Since the military ousted Morsi in 2013, militants have repeatedly set off explosives in Cairo, mostly targeting police and soldiers.
The blast came amid heightened security for an investment conference in the Red Sea resort of Sharm el-Sheikh, some 400 kilometres (250 miles) southeast of Cairo, which has attracted global leaders and businessmen.
The attack was a reminder of the lingering unrest President Abdel Fattah al-Sisi has tried to stamp out since taking charge.
The former army chief, who toppled Morsi in 2013 and then won a presidential election, has led a deadly crackdown on Morsi's supporters and sought to quell a militant insurgency in the Sinai Peninsula that has killed scores of policemen and soldiers.