CAIRO — In a raw contest between Egypt’s competing centers of power, legislators Tuesday defied the country’s highest court and its most senior generals by holding a brief session of the dissolved Parliament, heeding an order by President Mohammed Morsi in the face of opposition — but no overt obstacles from judges and the military.

Later, the Supreme Constitutional Court, which decides matters of constitutional principle, issued a statement saying that the president’s order was in effect illegal, because it defied the court’s earlier ruling justifying the dissolution.

The parliamentary session lasted only a few minutes, long enough for lawmakers to decide in a voice vote to take the military’s order dissolving Parliament to the Court of Cassation, a high appeals court that is one of a triumvirate of top courts in Egypt. Adding to the potential for judicial wrangling, the third top court, which rules on executive decisions, said Tuesday that its verdict would come next Tuesday.

The power struggle reflected dueling claims to Egypt’s emerging politics, with each side trying to frame the debate as a contest for ideals, legitimacy and democracy. The generals, backed by the court, argue that the new president must respect legal precedents and the institutions of the state. The new president, in turn, is calling on the generals to respect a popular will that was expressed through free elections.

But at its core, the fate of this Parliament is another chapter in the long-running battle between the Muslim Brotherhood — Morsi’s base and the dominant force in Parliament — and the military that intensified when the generals dissolved the legislature last month based on a court order and seized all lawmaking and executive authority.

The developments worry the United States and other powers, which are concerned that the standoff might imperil Egypt’s political future. Speaking during an Asian tour Tuesday, Reuters reported, U.S. Secretary of State Hillary Clinton appealed to the parties to talk out their differences.

“We strongly urge dialogue and concerted effort on the part of all to try to deal with the problems that are understandable but have to be resolved in order to avoid any kind of difficulties that could derail the transition that is going on,” Clinton said