Tens of thousands of Egyptians flocked to the Tahrir Square in Cairo on Tuesday evening against the supplementary constitutional declaration, sparking fresh instability ahead of the announcement of the presidential run-off winner.

Some protestors chanted "void constitutional declaration" and " people wants full powers for the president," while some others went to the recently dissolved People's Assembly, asking for transferring the executive authority to the coming president with full powers.

The army and the police forces are securing the People's Assembly building to prevent riots.

The Muslim Brotherhood, Wasat party, Free Front for Peaceful Change, campaigners for defeated presidential candidates Hamdeen Sabahi and Abou Foutouh, joined the protest.

On Sunday night, the ruling Supreme Council of the Armed Forces (SCAF) issued a supplementary constitutional declaration to retake legislative powers after the parliament was dissolved several days ago.

According to the document, the SCAF will exercise legislative powers until a new parliament is elected. The constitutional declaration amendments gave the SCAF great powers.

The SCAF shall also form a new panel within a week to draft a new constitution within three months if a reason bars the current assembly from fulfilling its task.

The document said that the new constitution shall be put to referendum within 15 days after being drafted and new parliamentary elections shall be called within a month after the approval of the new charter.

"The SCAF's supplementary constitution means that ... the constitution keeps the most important powers in the SCAF's hands, we want a president with powers not an image of a president," Ramy Mohamed, a member of the April 6 movement said.