Jordan's opposition Islamists urged Egyptians to hold street protests to condemn Wednesday's deadly crackdown on demonstrators loyal to ousted president Mohamed Morsi, warning the Arab world's fate was at stake.

Security forces supported by bulldozers moved in on empty two huge pro-Morsi protest camps in Cairo, leaving scores dead in a long-threatened crackdown.

"The blood of the innocent that the interior ministry and security services has shed today in Cairo appeals to you to fill the streets and thwart the conspiracy," the Islamic Action Front (IAF), political arm of Jordan's Muslim Brotherhood, said in a message addressed to Egyptians.

"The fate of Egypt and all Arabs and Muslims will be determined in line with your action. Do not let the coupists, the Zionists and US adminstration win," the IAF, the country's main political party, said on its website.

A demonstration was held in Amman outside the Egyptian embassy, where more than 1,000 people took part in a sit-in protest.

"Morsi, Morsi, down with the military coup," chanted the protesters as they waved Jordanian and Egyptian flags, holding banners that read "legitimacy is a read line."

"We came today to condemn the brutal massacre, which was the result of an Arab-US-Israeli conspiracy," Zaki Bani Rsheid, deputy leader of the Brotherhood, told AFP.

A security official said five Egyptians were arrested for taking part in the demonstration, adding without elaborating that "only Jordanians are allowed to demonstrate, according to the law."