Air attacks in the northern Sinai Peninsula have killed 16 armed fighters with ties to the Muslim Brotherhood, according to Egypt's military spokesman.
Colonel Ahmed Mohammed Ali said on Saturday that the raids had targeted hideouts of "terrorist, extremely dangerous" armed groups late on Friday in the eastern border town of Sheikh Zuweid.
It was the fourth such attack with a high death toll since armed fighters downed a military helicopter in a nearby area on January 24, killing all its crew members.
The Egyptian government has designated the Muslim Brotherhood a "terrorist" organisation.
The military has been waging a wide offensive in Sinai, which has become a hotbed for attacks on the military since Mohamed Morsi, who belongs to the Muslim Brotherhood, was toppled as president in July.
News of the air raids came as a new armed group, Ajnad Misr, claimed responsibility for the bombing of a police checkpoint near Cairo that wounded at least six people.
In a statement posted online, Ajnad Misr said it carried out the double bombing of a police vehicle on a bridge on Friday. The name of the group is Arabic for Egypt's Soldiers.
It said its "soldiers" had sent a message to the "criminal apparatus ... that they are not safe from retribution".
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The Ajnad Misr statement also said its fighters were monitoring the movements of the police and the headquarters from which "they launch their attacks every Friday killing and abusing innocent people".
The authenticity of the statement could not be verified, but it was posted on an al-Qaeda-affiliated website frequently used for claims of bombings and other attacks.
Ajnad Misr pledged to continue its attacks on policemen, urging them to defect and repent. It said it would not keep quiet until "justice prevails and a state accepted by God is established."
It said police should "leave the service before being overpowered, because the events are accelerating and that the chance to defect might not last long."
The wave of violence has raised concern that Egypt is evolving into a new front for regional armed groups.
Most of the recent attacks have been claimed by Sinai-based, al-Qaeda-inspired armed groups, but recently Ajnad Misr has also tried to establish a presence.
Muslim Brotherhood supporters again took to the streets on Friday to denounce the military-backed government and demand the reinstatement of Morsi.
Clashes broke in the capital and other provinces when police moved to disperse them, and the health ministry reported three were killed and 10 injured.
In a separate development, Morsi's predecessor Hosni Mubarak has fallen ill, delaying the resumption of a retrial on Saturday for his role in the death of protesters in 2011, a security official told Associated Press news agency.
The official, who spoke on condition of anonymity, did not give details of Mubarak's condition. But the Egyptian daily Al-Masry Al-Youm newspaper reported that Mubarak had suffered high blood pressure.