BEIRUT – Rebels on Friday pressed their broadest assault yet to drive President Bashar Assad’s forces out of Syria’s largest city, activists said, with fierce fighting erupting in an Aleppo neighborhood that is home to Kurds, an ethnic minority that has mostly stayed out of the civil war.

In Washington, U.S. Defense Secretary Leon Panetta said intelligence suggests Assad has moved some of Syria’s chemical weapons to better secure them. Panetta said the main sites are believed to be secure, though his comments indicated that there are lingering questions about what happened to some of the weapons.

On the diplomatic front, top representatives from Western nations and Middle East allies met Friday at the U.N. to urge Syria’s fractured opposition to unite. U.S. Secretary of State Hillary Rodham Clinton told the Friends of Syria group that the U.S. would deliver an additional $15 million in nonlethal aid and $30 million in humanitarian support, on top of more than $175 million already given to political opposition.