Ahmed Ali, a military spokesman, accused the Muslim Brotherhood group of masterminding the attack.

Unknown gunmen have killed six Egyptian soldiers in Cairo, signaling that violence that has been raging in the Sinai desert zone is now creeping into the heart of the country.

The military conscripts, positioned at a checkpoint in Cairo, were attacked at the break of dawn on Saturday. Ahmed Ali, a military spokesman, accused the Muslim Brotherhood group of masterminding the attack. If confirmed, it could mean that the Brotherhood's slow descent from open political participation towards violent covert action has now become distinctly discernable. The Brotherhood has faced a massive crackdown from the military after the ouster last year by the armed forces of Mohamed Morsy, Egypt's elected President.

Egypt's interim government has designated the Brotherhood as a terrorist organisation in December--a decision that was upheld by the court last month.

Egyptian security officials said that two bombs that were planted by the assailants following the shootout have been defused.

Armed Islamists have so far targeted the military mainly in the sparsely populated Sinai peninsula. But in recent months, their reach has expanded to the Nile Delta and the capital. An Al-Qaeda affiliated group, Ansar Beit Al-Maqdis, has so far claimed responsibility for most of the attacks on the army and police.

Saturday's strike follows street clashes on Friday between Brotherhood supporters and the armed forces in Cairo and Alexandria, Egypt's second largest city. Egypt state radio is reporting that protesters used Molotov cocktails, birdshot and fireworks during the clash on Friday in Cairo. Five Brotherhood members were arrested following the unrest in Alexandria.

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