There is growing international outrage over the killing of more than 90 civilians in the Syrian city of Houla.
In New York, UN leader Ban Ki-moon and UN-Arab League envoy Kofi Annan on May 26 called the killing a "brutal" breach of international law by the government.
U.S. National Security Council spokeswoman Erin Pelton said in Washington that the attack serves as a "vile testament to an illegitimate regime."
In London, British Foreign Secretary William Hague said he wants "a strong international response."
And French Foreign Minister Laurent Fabius said he would contact the Friends of Syria to try to arrange a meeting in Paris. No date has yet been set.
In Damascus, UN mission chief General Robert Mood said that monitors have counted 92 bodies, including 32 children, in Houla, north of Homs.
Syrian activists say the deaths were from shelling of Houla by regime forces midday on May 25 to dawn on May 26.