Egypt's Interior Ministry has accused the outlawed Muslim Brotherhood of forming a "military wing" to attack police and security forces.
A ministry spokesman appeared on Egyptian television Sunday and named 12 people who he said were members. He said five have been arrested.
The spokesman linked the alleged military wing to an attack that killed five policemen last month at a checkpoint south of Cairo. Video footage showed one of the accused confessing his involvement in that attack.
The Brotherhood, which backs ousted Islamist President Mohamed Morsi, says it rejected violence decades ago.
Egypt's military ousted Morsi in July and has branded the Brotherhood as a terrorist organization. Thousands of Muslim Brothers have been arrested and others have been driven underground.
Scores of Egyptian police and soldiers have been killed in bombings and by gunfire since the Egyptian military removed Morsi from office, after months of protests against his rule.
More than 1,000 pro-Morsi protestors have been killed in street demonstrations.
Morsi is currently on trial in Cairo on charges related to a prison escape during the 2011 uprising against then-President Hosni Mubarak.
Prosecutors also have accused him of inciting violence while he was president -- against anti-government protesters. He also faces trial for his alleged collaboration with the militant Palestinian group Hamas, which rules the Gaza Strip.
Human rights groups have accused Egypt's current military-backed government of widespread human rights abuses and of stifling dissent.