CAIRO - Egypt faced the prospect of fresh bloodshed on Thursday after the country's army-backed rulers signalled they would move soon to disperse thousands of supporters of deposed Islamist president Mohamed Morsi.

Activists from a group called "Third Square", which promotes a middle way in the rift between the Muslim Brotherhood and supporters of the army's overthrow of Egyptian President Mohamed Morsi, carry posters of key former army figures as they gather to oppose both parties at Sphinx Square in Cairo July 30, 2013. [Photo/Agencies]

With no sign of a negotiated end to weeks of violent confrontation, Egypt's interim government said two Cairo vigils by supporters of Morsi posed a threat to national security, citing "terrorism" and traffic disruption.

It ordered the interior ministry to take steps to "address these dangers and put an end to them," but gave no timeframe.

The announcement set up a showdown with the Muslim Brotherhood, which refuses to leave the streets until Egypt's first freely elected president is reinstated. Deposed by the army on July 3, Morsi remains in military detention at a secret location.

A move against his supporters, at two sit-in protests in Cairo, could bring a new round of bloodletting after security forces shot dead 80 Brotherhood followers at dawn on Saturday and plunged the Arab world's most populous nation deeper into turmoil.

The crackdown, coupled with criminal probes against Morsi and other Brotherhood leaders, has fuelled global concern that the military plans to crush the Islamist movement, which spent decades in the shadows before winning power in repeated elections after a 2011 uprising toppled autocrat Hosni Mubarak.

The fate of the Egyptian Brotherhood could shape that of Islamists across the Middle East at a time of transformation after a wave of popular revolts since 2011.

Wednesday's announcement appeared to undercut efforts by the European Union to negotiate a peaceful settlement.