Egypt's military on Monday said the constitution and the law must be upheld concerning the dissolution of parliament, raising tension after President Mohamed Morsi decided to reinstate the assembly.

The Supreme Council of the Armed forces (SCAF), which ruled Egypt until Morsi's election last month, underlined the "importance of the constitution in light of the latest developments," the official MENA news agency reported.

Only hours after the top court on Monday rejected a decree by Morsi to reinstate the parliament it had ruled invalid -- a ruling enforced by the SCAF -- the military said it was "confident that all state institutions will respect constitutional declarations."

MENA also quoted the SCAF statement as saying that it had only agreed to dissolve parliament after the Supreme Constitutional Court ruled that the "People's Assembly is invalid."

Islamists scored a crushing victory in Egyptian parliamentary elections that were held in three-stages from November last year, with the Muslim Brotherhood, Morsi's former organisation, heading the lower house.

But the military dissolved parliament last month after the top court made its controversial ruling, a day before the second round of the presidential poll that saw Morsi become Egypt's first democratically elected head of state.

The Supreme Constitutional Court had said certain articles in the law governing parliamentary elections were invalid, annulling the Islamist-led house.