"Chaos is not tomorrow, it is today, and we need to end it. We need to end it in a peaceful way and that means increased and concrete support to the Syrian National Coalition."
Islamic militants have been the most organized fighters battling government troops in the 22-month-old conflict in which more than 60,000 people have been killed. Their growing prominence has fueled fears that Muslim radicals might try to hijack the revolt, and has contributed to the West's hesitance to equip the opposition with sophisticated weapons.
In Beirut, U.N. humanitarian chief Valerie Amos said the situation in Syria was getting worse - that entire neighborhoods were being destroyed by the fighting.
Amos, who just returned from Syria, also reported human-rights abuses.
"I listen to the women who talk about what happened to them, to their families, the sexual abuse they have faced," Amos said in an interview.
"The indiscriminate shelling. The indiscriminate killing of people. This is a conflict that is happening essentially in towns and cities," she said.
Amos said she went last year to the once rebel-held neighborhood of Baba Amr in the central city of Homs. She said the entire neighborhood was destroyed and more than 70,000 people had left, but no one knew where they had gone.