Two minor explosions took place at two Cairo metro stations during early morning rush hour on Wednesday, Al-Ahram's Arabic news website reported.
At least three were injured, according to state news agency MENA and Al-Ahram.
The first blast, which took place in the northern Shubra station, was caused by an improvised bomb, interior ministry spokesman Abdel-Fattah Othman said. The second was a result of a sonic explosive placed in a rubbish bin at Ghamra station, on a different metro line.
The spokesperson denied earlier reports that four explosions had taken place at four different stations.
One of those injured in the blasts is a suspect, he added.
Metro sources and medics had earlier told Al-Ahram that four makeshift bombs had blown up at four metro stations, wounding at least three.
Security sources continue to comb the sites of the blasts for further explosives, the interior ministry said.