CAIRO — A decision by Egypt's new president to reinstate parliament was a bold challenge to the military that dissolved the house, but some politicians slammed it as a constitutional coup that shows no regard for the judiciary or democracy.

President Mohamed Morsi on Sunday issued a decree ordering the Islamist-led lower house back a month after the Supreme Constitutional Court found certain articles in the law on parliamentary elections to be invalid, and annulling it.

Days later, the Supreme Council of the Armed Forces (SCAF), which was running the country before Morsi became president, dissolved parliament based on the ruling.

"Morsi's decision to return parliament until new elections are held is the first step to reversing the constitutional declaration," said leftist activist Wael Khalil, adding that more steps had to be taken to "restore all authority to those elected."

The SCAF issued a constitutional declaration -- a temporary charter -- granting itself sweeping powers including legislative power, causing outrage among those who wanted the army to return to barracks after overseeing the transition from Hosni Mubarak's rule.

Morsi's decree was hailed by some who wanted the military out of politics and who saw that the constitutional declaration rendered the post of the elected president toothless.

"How can some be against the constitutional declaration... and when (the president) starts to take back his power from the military, they get angry?" asked writer and political commentator Alaa al-Aswany.

"President Morsi (elected) took legislative powers from SCAF (not elected) and gave it to the people's assembly (elected)," wrote long-time activist Ahmed Zahran on Twitter.

The presidential 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.

Some papers described Morsi's decision as a "political earthquake," forcing the powerful military to face off with the president for power.

"Morsi says to SCAF: Checkmate," read the headline of the independent daily Al-Watan, as Al-Tahrir, another daily, declared "Morsi defeats SCAF."

The decision also angered the Supreme Constitutional Court which rejected Morsi's decree and said its rulings were binding on all state institutions, insisting, however, that it is not "part of any political conflict."

But some slammed the president's decision as a "constitutional coup."

"The executive decision to bring back parliament shows a disregard for the judicial authority and takes Egypt into a constitutional coma and a conflict between the institutions," Nobel laureate and political dissident Mohamed ElBaradei wrote on Twitter.

The decree was slammed by some secular politicians who had criticised the Muslim Brotherhood's monopolisation of power since the start of the uprising.

"SCAF has to move against this constitutional coup: Egypt is not ruled by the Brotherhood's guidance council," said liberal MP Mohammed Abu Hamed.

"In any decent and democratic country, a president cannot disrespect the judiciary," said Rifaat al-Said, head of the leftist Al-Tagammu party.

"Whether Morsi likes it or not, he must respect the judiciary's decisions," he told state television.

The constitutional declaration issued by the army was described by the Muslim Brotherhood, from which Morsi stood down after his election, as a "soft coup," heightening tensions between the army and the Brotherhood after 15 months of political upheaval.

Some such as former presidential candidate Abdel Moneim Abul Fotouh found in Morsi's decision a gentle way out of that confrontation.

"Respect for the popular will by restoring the elected parliament and respect for the judiciary by holding parliamentary elections is the way out of this crisis," Abul Fotouh wrote on Twitter.