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At least 265 arrested in crackdown on Egypt's Muslim Brotherhood

Khaled Desouki / AFP - Getty Images

Policemen detain a Muslim Brotherhood supporter after a demonstration in Cairo's eastern Nasr City district on Friday.

CAIRO - At least 265 people, including 28 women, have been arrested across Egypt as the government deepens its crackdown on members of the ousted and now-banned Muslim Brotherhood, security sources said on Friday. 

Three people were killed in clashes between protesters and police after the government deployed police across Cairo in anticipation of further protests after Friday prayers.

Officials have issued increasingly harsh warnings against anyone participating in protests in support of the Muslim Brotherhood, the Islamist movement that propelled Mohamed Morsi to the presidency 18 months ago but has been driven underground since the army toppled him in July.

Some analysts warn the escalating crackdown could trigger further violence in a country that is already facing the worst internal strife in its modern history.

On Wednesday, the government formally listed the group as a terrorist organization after accusing it of carrying out a suicide bomb attack on a police station that killed 16 people.

The government's move gives authorities the power to charge any member of the Brotherhood with belonging to a terrorist group, as well as anyone who finances the group or promotes it "verbally, or in writing."

The Brotherhood condemned the attack on the police station, while a Sinai-based group claimed responsibility for it. 

The group has also continued its protests, and has most recently focused on demonstrating at universities, where students have clashed with police.

Meanwhile, military chief Gen. Abdel-Fattah el-Sissi, the man who removed Morsi and is now the country's most powerful person, vowed to "stand steadfast in confronting terrorism." 

"Don't let any of the incidents happening now affect the will of Egyptians. Never," he told military graduates Thursday. "Anyone harms you will be wiped from the face of Earth." 

NBC News' F. Brinley Bruton, and Reuters and The Associated Press contributed to this report.