Egypt's Muslim Brotherhood called on Arab and other world powers on Monday to intervene in Syria after 108 people were killed in the town of Houla in an attack it blamed on President Bashar al-Assad's forces.
Images of the bloodied bodies of children and others slain in Houla have shocked the world and highlighted the failure of a six-week-old U.N.-backed ceasefire to stop the violence in the 14-month uprising against Assad's rule.
"The Muslim Brotherhood calls on Arab, Islamic and international governments ... and the people of the free world to intervene to stop these massacres, especially after the failure of international forces and international monitoring to stop them," spokesman Mahmoud Ghozlan said in a statement.
He did not say exactly what the world should do about Syria.
The Muslim Brotherhood's candidate in Egypt's presidential elections topped last week's first-round poll, unofficial results show. The Islamist group already dominates both houses of parliament after earlier elections.
The U.N. Security Council on Sunday condemned Assad's government for firing heavy weapons at Houla.
Ghozlan also called on Syrians to put aside their differences and unite to "bring down the regime, make the revolution succeed and free the heroic Syrian people".
He said the Syrian government's crimes were worse than those of Genghis Khan, a warrior who founded the Mongol empire in the 13th century.
Syria's Muslim Brotherhood is part of the opposition to Assad, whose father, the late President Hafez al-Assad, bloodily crushed an armed Islamist uprising in the 1980s.
The Syrian and Egyptian branches of the Brotherhood share the same ideology but have no direct organisational links.