Egypt's association of judges called Saturday for the judicial system to come to a halt to fight an assertion of near-absolute power by the nation's first democratically elected president, setting the stage for a confrontation between the courts and a man who has said his will is not subject to appeal.

Judges across the country vowed to strike, and lawyers filed several legal challenges to the move by President Mohammed Morsi, who has said he is assuming broad powers temporarily to combat entrenched remnants of the former authoritarian government. The constitutional court, meanwhile, hinted that it may weigh in on the matter, directly challenging the man who has tried to sideline them.

The dispute — which was rapidly emerging as a divide between Egypt's secularists and political Islamists — showed no sign of diminishing Saturday, raising questions about Egypt's fragile democratic transition.

With hundreds of protesters camping out in Tahrir Square and vowing not to leave until the president rescinds his decrees, and Morsi's Islamist backers and his opponents both planning to mobilise dueling demonstrations in the coming week, compromise was nowhere in sight.

In a Cairo hall packed with lawyers and judges, the man who was prosecutor general until Morsi booted him from office Thursday vowed that he would fight the sidelining of the courts if it cost him his life.

"These groups do not know what is righteous," Abdel Meguid Mahmoud said to cheers. An appointee of former president Hosni Mubarak, Mahmoud has presided over the acquittals of many officials of the old autocratic government, and Islamists and liberal revolutionaries alike had wanted him gone. On Saturday, however, many of those secularists found themselves on his side, with the country's leading liberal politicians and human rights organisations uniting in opposition to Morsi's measures.

Outside the country's main administrative courts, protesters fought with police, who fired tear gas at them. Egypt's judges' association, many of whose members were appointed by Mubarak, called the moves an "unprecedented assault on the judiciary," and the head of the judges' group in the coastal city of Alexandria said that courts there were already on strike.

Morsi issued his decrees just a day after garnering international praise for helping bring about a cease-fire between the Gaza Strip and Israel following a week of bloody conflict. That enthusiasm quickly dimmed after his announcement, including in the United States, where the State Department said Friday that the actions "raise concerns." But it was not clear whether US officials would be willing to jeopardise Egypt's role as a broker between Israel and Gaza's Hamas rulers by pushing too hard on the domestic front.

Morsi has said that the steps were necessary to prevent what he termed a small group of "weevils" from eating away at democratic gains of the past two years. The constitutional court had appeared poised to dissolve within weeks the body writing a new constitution, as well as the Islamist-dominated upper house of parliament. The court had already dismissed the lower house in June, shortly before Morsi was inaugurated. He has said he will give up his powers once a new constitution and parliament are in place.

"All the obstacles that have occurred during the transitional period . . . were made by remnants of the former regime to discredit the revolution and hinder its movement," the Muslim Brotherhood's political wing, a Morsi ally, said in a statement Saturday.

Morsi backers said that the constitutional court had been harming democracy, not helping it, by issuing dramatic rulings that shut down new institutions as they emerged.

The constitutional court, meanwhile, held an emergency meeting of its own Saturday. It said afterward that it was not going to comment on the edicts because legal cases "might be referred to the court concerning the constitutional declaration."

But that in itself was a challenge to Morsi, since his emendations to Egypt's transitional constitution said that no court was permitted to question any of his decisions. Legal analysts said that if the court finds that the president is not permitted to amend the constitution, it may also have to void an August decision by Morsi to strip the military of its power to declare legislation.

"Egypt has gone so far into a constitutional twilight zone . . . you make up the rules as you go along," said Elijah Zarwan, a Cairo-based Egypt expert at the European Center for Foreign Relations. "Basically, between Morsi and the Constitutional Court there is a confrontation of dueling legitimacies."