CAIRO (AP) — A newly formed militant group claimed responsibility on Saturday for the bombing of an Egyptian police checkpoint near Cairo that wounded six people, as health authorities said that three people were killed in clashes between Islamists and police a day earlier.

Muslim Brotherhood supporters took to the streets Friday to denounce the military-backed government and demand the reinstatement of deposed President Mohammed Morsi, ousted in a military coup on July 3. Clashes broke in the capital and other provinces when police moved to disperse them. The Health Ministry said three were killed and 10 injured.

The overthrow of the Islamist Morsi has sparked a wave of militant attacks targeting mainly military and police. Most of the attacks have been claimed by a Sinai-based, al-Qaeda-inspired militant group. But recently a new organization, Ajnad Misr — Arabic for Egypt’s Soldiers — has also tried to establish a presence.

In a statement posted late Friday on a jihadi website the group said it carried out the double bombing of a police vehicle on a bridge earlier in the day.

It said its “soldiers” had sent a message to the “criminal apparatus … that they are not safe from retribution.”

It 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 group issued its first statement last week, claiming responsibility for several such bombings, including one on Jan. 24 that hit police just as they returned from clashes with Brotherhood supporters. Pro-Morsi protesters frequently demonstrate early Friday afternoons after Muslim prayers.

Ajnad Misr vowed 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 authenticity of the statement could not be verified, but it was posted on an al-Qaeda-affiliated website frequently used for militant claims.

The wave of violence has raised concern that Egypt is evolving into a new front for regional jihadi groups.

Meanwhile, Morsi’s predecessor Mubarak had a sudden health scare when he returned to trial in connection with the killings of protesters during the 2011 uprising that led to his downfall, according to a security official.

The official gave no details of Mubarak’s condition during the resumption of the retrial. He spoke on condition of anonymity because he was not authorized to speak to the press.

Egyptian daily Al-Masry Al-Youm reported that the ousted longtime autocrat had suffered high blood pressure.

Mubarak is being retried over charges of failing to stop the killings of protesters after his earlier life-imprisonment sentence was canceled on appeal. The trial, which has lasted more than two years, comes at a time his successor Morsi, faces several trials of his own, including one for allegedly inciting the murder of protesters.

The 85-year-old Mubarak was treated in 2010 for cancer of the gallbladder and pancreas.

Copyright 2014 The Associated Press.