Egypt's parliament speaker has invited the lower house to convene on Tuesday following a decision by the president to reinstate the assembly, in a challenge to the military that disbanded the legislature.
Saad al-Katatni "has called on parliament to convene at 2:00 pm (1200 GMT) on Tuesday," the official MENA news agency reported.
The call by Katatni, who belongs to the Muslim Brotherhood, comes after President Mohamed Morsi ordered the return of the Islamist-led parliament which was dissolved by the Supreme Council of the Armed Forces (SCAF) based on a court ruling.
The move has put Morsi, who stepped down from the Brotherhood when he was sworn in last month, on a collision course with the SCAF that ruled the country after Hosni Mubarak was ousted by a popular uprising last year.
Morsi's decree also stipulates the organisation of new parliamentary elections two months after the approval by referendum of the country's new constitution and the adoption of a new law regulating parliament.
The presidential decision was likely to heighten tensions with the military, although both Morsi and Field Marshal Hussein Tantawi who heads SCAF appeared together at a military cadet graduation ceremony on Monday.
The SCAF had convened an urgent meeting "to discuss the presidential measures" state television said.
The High Judicial Council and the Constitutional Court were also meeting on Monday to discuss the constitutionality of Morsi's decision.
"Morsi says to SCAF: Check mate," read the headline of the independent daily Al-Watan, as Al-Tahrir, another daily, declared "Morsi defeats SCAF."
The move, described by some papers as a "political earthquake," has also put Morsi on a collision course with the country's judiciary and some secular parties.
"In any decent and democratic country, a president cannot disrespect the judiciary," said Rifaat al-Said, the head of the leftist Al-Tagammu party.
"Whether Morsi likes it or not, he must respect the judiciary's decisions," he told state television.
Said said a march to parliament would be organised later on Monday, and stressed that "several parties will boycott parliament's sessions."
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The military dissolved parliament last month after Egypt's top court made its controversial ruling, a day before the second round of the presidential poll that saw the Islamist Morsi become Egypt's first democratically elected head of state.
The powerful Muslim Brotherhood, from which Morsi stood down after his election, at the time described the move as a "soft coup," accusing the military of seeking to monopolise power and demanding a referendum.
The Supreme Constitutional Court had said certain articles in the law governing parliamentary elections were invalid, annulling the Islamist-led house.
It also ruled as unconstitutional the political isolation law, which sought to bar senior members of Mubarak's regime and top members of his now-dissolved party from running for public office for 10 years.
Morsi beat Ahmed Shafiq -- Mubarak's last prime minister -- in the presidential election.
The SCAF issued a constitutional declaration granting the military sweeping powers and in the absence of a parliament -- in which nearly half of the seats had been won by the Muslim Brotherhood and another quarter by hardline Salafists -- it assumed legislative power.
SCAF's document, which rendered the president's post toothless, had caused outrage among those calling for the military to return to their barracks.
Instead of being sworn in before parliament, the 60-year-old Morsi took the oath on June 30 before the constitutional court.
US President Barack Obama will meet Egypt's new president at the UN General Assembly in New York in September, an official in Washington told AFP on Sunday.
Secretary of State Hillary Clinton, who is to visit Cairo on July 14, has congratulated Morsi on his election but cautioned that his victory was just a first step towards true democracy.
Clinton's deputy, Bill Burns, was in Cairo on Sunday on the last day of a three-day visit for a wide range of meetings.
Despite Morsi's Islamist background, the confirmation of his election brought relief to Obama's administration, which feared that the military would not accept his victory and provoke new chaos in Egypt.
Morsi put Washington further at ease shortly after his victory announcement when he pledged to be a leader for all Egypt, where around 10 percent of the population is Christian, and to honour the country's 1979 peace treaty with Israel.