Hundreds of Muslim Brotherhood supporters have stormed the Giza governorate building in Cairo in retribution for the bloody crackdown on pro-Morsi protesters that killed over 500 people and injured 3,000 pmore.

Pictures of the government building on fire and hundreds of people fleeing the scene were posted on social media, as news emerged that supporters of deposed president Mohamed Morsi are planning to march through the Egyptian capital in protest at yesterday's violence.

The Muslim Brotherhood confirmed marches "are planned from al-Iman mosque", where hundreds of charred and mutilated bodies were taken after the clashes which began when police officers tried to clear protest camps at Nasr City and Rabaa al-Adawiya.

Brotherhood spokesman Gehad El-Haddad said the anti-coup alliance has suffered a "very strong blow" from the security crackdown, adding that the anger "is beyond control now". Haddad hinted that the only way out is dialogue based on "constitutional legitimacy" - to which ousted president Morsi holds the key.

"We will always be non-violent and peaceful. We remain strong, defiant and resolved," Haddad wrote on his Twitter feed. "We will push [forward] until we bring down this military coup."

The Egyptian Health Ministry's figure of 525 dead is likely to rise as Reuters claims to have counted 228 further bodies at a northeast Cairo mosque. The Brotherhood claims the true death toll is actually far higher, with almost 2,000 people killed in the "massacre".

Egypt's liberal vice-president Mohamed El Baradei, a respected politician and Nobel laureate, resigned in protest against the crackdown, while the military-installed government has declared a one-month of state of emergency and imposed a dusk-to-dawn curfew on Cairo and 10 other provinces which rose up in response to the violence.

The bloodbath has drawn international condemnation, with Turkish prime minister Recep Tayyip Erdogan calling for the UN Security Council to convene. Meanwhile, Denmark has decided to suspend aid to Egypt worth $5.3m.

"Denmark has two projects in direct collaboration with the Egyptian government and public institutions, and they are now going to be suspended," Christian Friis Bach, Danish aid development minister, said.

However Egypt's prime minister Hazem El Beblawi has defended the police crackdown on Cairo's Morsi camps, saying that officers "observed the highest degrees of self-restraint" in clearing the settlements.