Thousands gathered in Cairo in protest of a ruling by Egypt's Supreme Constitutional Court to freeze a decree issued by President Mohamed Morsi to reinstate the Islamist-led parliament.
"The court ruled to halt the president's decision to recall the parliament," Judge Maher el-Beheiry said in court on Tuesday.
Morsi, a former member of the powerful Muslim Brotherhood, ordered on Sunday for the lower house to reconvene, just eight days after taking office.
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Tuesday's ruling came hours after the 508-seat chamber held a brief session, following the president's request for the legislators to convene.
They voted to seek further judicial opinions on the court's decision that had invalidated one-third of the lawmakers because of voting irregularities.
Morsi's move highlighted the power struggle between the presidency and the Supreme Constitutional Court, which last month said certain articles in the law governing the parliament elections were invalid, annulling the lower house.
News of the verdict was greeted with chants of "batel", or illegitimate, by thousands of Morsi supporters gathered in Cairo's Tahrir Square.
"Everything now depends on the reaction by parliament," said Al Jazeera's Sherine Tadros, reporting from Cairo.
"The Supreme Court has once again reiterated that the parliament is dissolved," our correspondent said. "It's the third decision by them saying that Morsi's decison to reinstate the parliament was illegal. They cannot say it in any more certain terms than that."
"They're saying that the parliament sessions cannot continue, which would mean legislative powers would stay in the hands of the armed forces - in this power struggle between the military and the president."
Islamist parties, including the Brotherhood's Freedom and Justice Party, which Morsi headed before becoming president, and Salafist parties, attended the parliamentary session on Tuesday.
"We are gathered today to review the court rulings, the ruling of the Supreme Constitutional Court," speaker Saad al-Katatni said.
"I want to stress, we are not contradicting the ruling, but looking at a mechanism for the implementation of the ruling of the respected court. There is no other agenda today," he added.
Lawyers representing Morsi criticised the court's latest decision and said Tuesday's ruling was a political move that would further complicate the crisis.
"This ruling is null and void," lawyer Abdel Moneim Abdel Maqsud told reporters while another member of the team, Mamduh Ismail, called it a "political decision".
Sherine Tadros reports from Cairo
Meanwhile, thousands of protesters rallied on Tuesday evening in Tahrir Square, the hub of the revolution, in support of Morsi and chanting "Down with the military" and other slogans hostile to judges and TV anchors they accuse of being anti-Islamist.
Earlier in the day opponents of Morsi's decree had protested outside the presidential palace.
Morsi's decree was hailed by those who want to see the army return to barracks, but it was criticised by those who fear an Islamist monopolisation of power as a "constitutional coup".
Katatni said parliament had referred the case invalidating the house to the Court of Cassation.
US Secretary of State Hillary Clinton, who is due to visit Cairo on Saturday, urged all parties to engage in dialogue.
"We urge that there be intensive dialogue among all of the stakeholders in order to ensure that there is clear path for them to be following," she said in Vienna.
The Egyptian people should "get what they protested for and what they voted for, which is a fully elected government making the decisions for the country going forward", she added.