Egypt's military chief called for mass rallies on Friday to give the army a mandate to confront violence following the overthrow of Islamist President Mohamed Mursi, appearing to up the ante against the Muslim Brotherhood.
General Abdel Fattah al-Sisi, who deposed Mursi on July 3 and replaced his government with a new interim administration, also said there would be no retreat from the army-backed roadmap that envisions parliamentary elections within six months.
"I ask ... that next Friday all honest and trustworthy Egyptians must come out," Sisi said in remarks broadcast live by state media. "Why come out? They come out to give me the mandate and order that I confront violence and potential terrorism."
A senior member of Mursi's Muslim Brotherhood movement, Essam El-Erian, said Sisi's appeal was a threat, but vowed that it would not halt protests to back the ousted president.
"Your threat will not prevent millions from continuing to gather," Erian wrote on Facebook.
Sisi's remarks at a military graduation ceremony followed an overnight bomb attack on a police station in Mansoura, 110 km (68 miles) north of Cairo, that killed one person and wounded two dozen others.
A government spokesman condemned it as a terrorist attack.
Mursi's Islamist backers have accused security forces of conspiring to blame them for the bombing.
In a statement, they warned of "an apparent plan by security and intelligence agencies to plot violent attacks to terrorize citizens and then attempt to link these incidents to the peaceful protesters".
The authorities have accused Mursi's supporters of employing violence since he was removed from power following mass protests against his rule. More than 100 people, most of them Mursi supporters, have been killed since then. The Muslim Brotherhood says it has not and will not resort to violence.
With many of its top leaders in jail and Mursi in military detention, the Brotherhood says its supporters are being attacked by plain-clothes agents deployed by the authorities - a charge denied by security officials.
Overnight, at least two more people died in the streets of Cairo in protests against Mursi's ouster. That followed nine fatalities in the capital on Tuesday - bloodshed underscoring the depth of the crisis facing Egypt and the interim government.