Des opposants au président égyptien Mohamed Morsi ont entamé vendredi soir un sit-in sur l'emblématique place Tahrir au Caire pour demander au dirigeant islamiste de revenir sur sa décision de renforcer considérablement ses pouvoirs.

"Toutes les forces politiques révolutionnaires se sont mises d'accord pour commencer un sit-in vendredi", a déclaré dans un communiqué le Courant populaire dirigé par Hamdeen Sabbahi, candidat de gauche arrivé troisième à l'élection présidentielle de juin, appelant à une grande manifestation mardi.

Jusqu'à présent, 26 mouvements et partis politiques ont accepté de prendre part au sit-in, ont indiqué les organisateurs à l'AFP.

M. Morsi s'est arrogé jeudi dans une "déclaration constitutionnelle" le droit de "prendre toute décision ou mesure pour protéger la révolution" de 2011, une initiative qui, selon ses partisans, devrait permettre de stabiliser la transition démocratique du pays.

Mais cette décision est considérée par l'opposition comme une menace pour la marche vers la démocratie et un "coup d'Etat" remettant en cause les acquis de la révolte qui a renversé en 2011 le président autocratique Hosni Moubarak.

Les photos des manifestations en Égypte compilées par nos collègues du HuffPost américain
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  • Protesters storm an office of Egyptian President Mohammed Morsi's Muslim Brotherhood Freedom and Justice party and set fires in the Mediterranean port city of Alexandria, Egypt, Friday, Nov. 23, 2012. (AP Photo/Amira Mortada, El Shorouk Newspaper)

  • Thousands of Egyptian demonstrators march towards Cairo's landmark Tahrir square during a protest against Egypt's Islamist President Mohamed Morsi's power grab, on November 23, 2012. (GIANLUIGI GUERCIA/AFP/Getty Images)

  • Egyptian supporters and opponents of President Mohamed Morsi clash in the Mediterranean coastal city of Alexandria on November 23, 2012. (-/AFP/Getty Images)

  • Egyptians beat a young boy during clashes between supporters and opponents of President Mohamed Morsi, in the northern coastal city of Alexandria on November 23, 2012. (-/AFP/Getty Images)

  • Thousands of Egyptian march through the streets of Cairo to protest against Egypt's Islamist President Mohamed Morsi's power grab, on November 23, 2012. (GIANLUIGI GUERCIA/AFP/Getty Images)

  • Egyptian supporters and opponents of President Mohamed Morsi clash in the Mediterranean coastal city of Alexandria on November 23, 2012. (-/AFP/Getty Images)

  • Thousands of Egyptian demonstrators march towards Cairo's landmark Tahrir square during a protest against Egypt's Islamist President Mohamed Morsi's power grab, on November 23, 2012. Morsi has assumed temporary sweeping powers that supporters say will cut back a turbulent and seemingly endless transition to democracy, but outraged critics say he has now become a dictator. AFP PHOTO/GIANLUIGI GUERCIA (Photo credit should read GIANLUIGI GUERCIA/AFP/Getty Images)

  • Egyptian demonstrators, flying their national flag, arrive in Cairo's landmark Tahrir square during a protest against Egypt's Islamist President Mohamed Morsi's power grab, on November 23, 2012. (GIANLUIGI GUERCIA/AFP/Getty Images)

  • Thousands of Egyptian demonstrators march towards Cairo's landmark Tahrir square during a protest against Egypt's Islamist President Mohamed Morsi's power grab, on November 23, 2012. (GIANLUIGI GUERCIA/AFP/Getty Images)

  • Supporters of Egyptian President Mohammed Morsi chant slogans and wave is campaign posters and a national flag outside the Presidential Palace in Cairo, Egypt, Friday, Nov. 23, 2012. (AP Photo/Ahmed Gomaa)

  • Supporters of Egyptian President Mohammed Morsi chant slogans and wave his campaign posters outside the Presidential palace in Cairo, Egypt, Friday, Nov. 23, 2012. (AP Photo/Ahmed Gomaa)

  • Supporters of Egyptian President Mohammed Morsi chant slogans and wave his campaign posters outside the Presidential palace, background, in Cairo, Egypt, Friday, Nov. 23, 2012. (AP Photo/Ahmed Abd el Fatah)

  • Egyptian protesters opposed to President Mohammed Morsi break into the offices of the Freedom and Justice Party, the political wing of the Muslim Brotherhood, in Alexandria, Egypt, Friday, Nov. 23, 2012. (AP Photo/Tarek Fawzy)

  • Protesters hurl stones during clashes between supporters and opponents of President Mohammed Morsi in Alexandria, Egypt, Friday, Nov. 23, 2012. (AP Photo/Tarek Fawzy)

  • Protesters hurl stones during clashes between supporters and opponents of President Mohammed Morsi in Alexandria, Egypt, Friday, Nov. 23, 2012. (AP Photo/Tarek Fawzy)

  • Protesters hurl stones during clashes between supporters and opponents of President Mohammed Morsi in Alexandria, Egypt, Friday, Nov. 23, 2012. (AP Photo/Tarek Fawzy)

  • Egyptian protesters opposed to president Mohammed Morsi take cover during clashes with Morsi supporters near Tahrir Square in Cairo, Egypt, Friday, Nov. 23, 2012. (AP Photo/Mohammed Asad)

  • Egyptian protesters opposed to president Mohammed Morsi try to breach a building during clashes near Tahrir Square in Cairo, Egypt, Friday, Nov. 23, 2012. (AP Photo/Mohammed Asad)

  • Egyptian protesters chant anti-government slogans and wave a national flag in Tahrir Square, Friday, Nov. 23, 2012. Supporters and opponents of Egypt's Islamist President Mohammed Morsi staged rival rallies Friday after he assumed sweeping new powers, a clear show of the deepening polarization plaguing the country. (AP Photo/Maya Alleruzzo)

  • Protesters rush a wounded comrade to a field hospital in Tahrir Square, Friday, Nov. 23, 2012. (AP Photo/Maya Alleruzzo)

  • An Egyptian protester chants slogans and holds a cross and a Quran in Tahrir Square, Friday, Nov. 23, 2012. (AP Photo/Maya Alleruzzo)

  • Supporters of Egyptian President Mohammed Morsi chant slogans and wave is campaign posters and a national flag outside the Presidential Palace in Cairo, Egypt, Friday, Nov. 23, 2012. (AP Photo/Ahmed Gomaa)

  • Supporters of Egyptian President Mohammed Morsi chant slogans and wave his campaign posters outside the Presidential palace in Cairo, Egypt, Friday, Nov. 23, 2012. (AP Photo/Ahmed Gomaa)

  • Mohamed El Baradei, Amr Moussa

    In this Thursday, Nov. 22, 2012 photo, former director of the U.N.'s nuclear agency and Nobel peace laureate, Mohamed El Baradei, left, and former Egyptian Foreign Minister and presidential candidate, Amr Moussa, raise their hands in solidarity after addressing a news conference flanked by other prominent politicians, not shown, from outside the Muslim Brotherhood, to decry what was interpreted as a de facto declaration of emergency law by Egyptian President Mohammed Morsi, in Cairo Egypt. (AP Photo/Mostafa El Shemy)

  • Mohamed El Baradei, Amr Moussa

    In this Thursday, Nov. 22, 2012 photo, former Egyptian presidential candidate, Hamdeen Sabahi, left, speaks to former director of the U.N.'s nuclear agency and Nobel peace laureate, Mohamed El Baradei, during a news conference flanked by other prominent politicians, not shown, from outside the Muslim Brotherhood, to decry what was interpreted as a de facto declaration of emergency law by Egyptian President Mohammed Morsi, in Cairo Egypt. (AP Photo/Mostafa El Shemy)

  • Mohammed Morsi

    In this Friday, July 13, 2012 photo, Egyptian President Mohammed Morsi speaks to reporters during a joint news conference with Tunisian President Moncef Marzouki, unseen, at the Presidential palace in Cairo, Egypt. (AP Photo/Maya Alleruzzo)