Ajnad Misr, a militant group operating in Egypt, claimed responsibility for a blast at Cairo University that injured 11 on Wednesday.
The operation was part of a "Retribution is Life" campaign that targets "criminal," security forces, the group, whose name means "Soldiers of Egypt" in Arabic, said in a statement released on its Twitter account.
"This blessed operation comes after a rise in killing and maltreatment incidents against students. And we have been avoiding targeting the criminal apparatus near universities ... til it was proven that they are carrying out systematic crimes [against students] without justification," it said.
The group also pointed out that it was keen on "minimising the power" of the blast, so as not to affect civilians.
The bomb, that officials said was aimed clearly at policemen stationed outside the university, injured six police and five civilians. It was planted in a gas pipeline and prosecutors said it was likely to have been detonated using a mobile phone.
The group said the blast took place at the same location where Brigadier-General Tarek El-Mergawi was killed, also following a bomb explosion in April.
Cairo University, along with other campuses nationwide, has been the scene of unrest since the start of the new academic year two weeks ago, with recurrent clashes occurring between police and alleged Islamist students protesting against the government.
One student was killed by birdshot following clashes with police at the Faculty of Engineering in Alexandria University, marking the first death in such clashes this year.
So far, police have stormed at least five universities and arrested over 180 students.
The students, many loyalists of the banned Muslim Brotherhood, are protesting against the current government, saying it is part of a "coup" that ousted Islamist President Mohamed Morsi in July 2013.
Morsi was ousted by the military amid nationwide popular protest against his rule.
Ajnad Misr had already claimed responsibility for planting bombs near Ittihadiya Presidential Palace on 30 June that killed two police officers, in addition to a blast outside the foreign ministry in Cairo in September that also killed two policemen.
Egyptian authorities have been battling a mounting insurgency, mainly based in the Sinai Peninsula but that has also spilled over into Delta governorates and the capital, Cairo.
Militant attacks have killed hundreds of police and army troops, while civilians have also died in the violence.